diff --git a/x-pack/plugins/synthetics/server/feature.ts b/x-pack/plugins/synthetics/server/feature.ts
index 4c2fa529f4690..ac5bce8a6b790 100644
--- a/x-pack/plugins/synthetics/server/feature.ts
+++ b/x-pack/plugins/synthetics/server/feature.ts
@@ -11,7 +11,7 @@ import { SYNTHETICS_RULE_TYPES } from '../common/constants/synthetics_alerts';
 import { privateLocationsSavedObjectName } from '../common/saved_objects/private_locations';
 import { PLUGIN } from '../common/constants/plugin';
 import { UPTIME_RULE_TYPES } from '../common/constants/uptime_alerts';
-import { umDynamicSettings } from './saved_objects/uptime_settings';
+import { settingsObjectType } from './saved_objects/uptime_settings';
 import { syntheticsApiKeyObjectType } from './saved_objects/service_api_key';
 
 export const uptimeFeature = {
@@ -32,7 +32,7 @@ export const uptimeFeature = {
       api: ['uptime-read', 'uptime-write', 'lists-all', 'rac'],
       savedObject: {
         all: [
-          umDynamicSettings.name,
+          settingsObjectType,
           syntheticsMonitorType,
           syntheticsApiKeyObjectType,
           privateLocationsSavedObjectName,
@@ -61,7 +61,7 @@ export const uptimeFeature = {
         all: [],
         read: [
           syntheticsParamType,
-          umDynamicSettings.name,
+          settingsObjectType,
           syntheticsMonitorType,
           syntheticsApiKeyObjectType,
           privateLocationsSavedObjectName,
diff --git a/x-pack/plugins/synthetics/server/lib.test.ts b/x-pack/plugins/synthetics/server/lib.test.ts
new file mode 100644
index 0000000000000..0ce1f79607846
--- /dev/null
+++ b/x-pack/plugins/synthetics/server/lib.test.ts
@@ -0,0 +1,140 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { UptimeEsClient } from './lib';
+import { savedObjectsClientMock, uiSettingsServiceMock } from '@kbn/core/server/mocks';
+import { elasticsearchClientMock } from '@kbn/core-elasticsearch-client-server-mocks';
+
+describe('UptimeEsClient', () => {
+  let uptimeEsClient: UptimeEsClient;
+  const savedObjectsClient = savedObjectsClientMock.create();
+  const esClient = elasticsearchClientMock.createClusterClient().asInternalUser;
+
+  beforeEach(() => {
+    uptimeEsClient = new UptimeEsClient(savedObjectsClient, esClient);
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  describe('search', () => {
+    it('should call baseESClient.search with correct parameters', async () => {
+      const mockSearchParams = {
+        body: {
+          query: {
+            match_all: {},
+          },
+        },
+      };
+
+      const result = await uptimeEsClient.search({
+        body: {
+          query: {
+            match_all: {},
+          },
+        },
+      });
+
+      expect(esClient.search).toHaveBeenCalledWith(
+        {
+          index: 'heartbeat-8*,heartbeat-7*',
+          ...mockSearchParams,
+        },
+        { meta: true }
+      );
+      expect(result).toEqual({
+        body: {},
+        headers: {
+          'x-elastic-product': 'Elasticsearch',
+        },
+        meta: {},
+        statusCode: 200,
+        warnings: [],
+      });
+    });
+
+    it('should throw an error if baseESClient.search throws an error', async () => {
+      const mockSearchParams = {
+        body: {
+          query: {
+            match_all: {},
+          },
+        },
+      };
+      const mockError = new Error('Search error');
+      esClient.search.mockRejectedValueOnce(mockError);
+
+      await expect(uptimeEsClient.search(mockSearchParams)).rejects.toThrow(mockError);
+      expect(esClient.search).toHaveBeenCalledWith(
+        {
+          index: 'heartbeat-8*,heartbeat-7*',
+          ...mockSearchParams,
+        },
+        { meta: true }
+      );
+    });
+  });
+
+  describe('count', () => {
+    it('should call baseESClient.count with correct parameters', async () => {
+      const mockCountParams = {
+        index: 'example',
+      };
+
+      const result = await uptimeEsClient.count(mockCountParams);
+
+      expect(esClient.count).toHaveBeenCalledWith(mockCountParams, { meta: true });
+      expect(result).toEqual({
+        indices: 'heartbeat-8*,heartbeat-7*',
+        result: {
+          body: {},
+          headers: {
+            'x-elastic-product': 'Elasticsearch',
+          },
+          meta: {},
+          statusCode: 200,
+          warnings: [],
+        },
+      });
+    });
+
+    it('should throw an error if baseESClient.count throws an error', async () => {
+      const mockCountParams = {
+        index: 'example',
+      };
+      const mockError = new Error('Count error');
+      esClient.count.mockRejectedValueOnce(mockError);
+
+      await expect(uptimeEsClient.count(mockCountParams)).rejects.toThrow(mockError);
+      expect(esClient.count).toHaveBeenCalledWith(mockCountParams, { meta: true });
+    });
+  });
+
+  describe('getInspectEnabled', () => {
+    it('should return false if uiSettings is not available', async () => {
+      const result = await uptimeEsClient.getInspectEnabled();
+
+      expect(result).toBe(false);
+    });
+
+    it('should return the value from uiSettings if available', async () => {
+      const mockUiSettings = uiSettingsServiceMock.createClient();
+      uptimeEsClient.uiSettings = {
+        client: mockUiSettings,
+      } as any;
+
+      // @ts-expect-error
+      mockUiSettings.get.mockReturnValue(true);
+
+      await uptimeEsClient.getInspectEnabled();
+
+      expect(uptimeEsClient.isInspectorEnabled).toBe(true);
+      expect(mockUiSettings.get).toHaveBeenCalledWith('observability:enableInspectEsQueries');
+    });
+  });
+});
diff --git a/x-pack/plugins/synthetics/server/saved_objects/migrations.test.ts b/x-pack/plugins/synthetics/server/saved_objects/migrations.test.ts
deleted file mode 100644
index ba97a9753f86a..0000000000000
--- a/x-pack/plugins/synthetics/server/saved_objects/migrations.test.ts
+++ /dev/null
@@ -1,165 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0; you may not use this file except in compliance with the Elastic License
- * 2.0.
- */
-import { add820Indices, remove890Indices } from './migrations';
-import { SavedObject, SavedObjectMigrationContext } from '@kbn/core/server';
-import { DynamicSettingsAttributes } from '../runtime_types/settings';
-
-describe('add820Indices migration', () => {
-  const context = { log: { warning: () => {} } } as unknown as SavedObjectMigrationContext;
-
-  const makeSettings = (heartbeatIndices: string): SavedObject<DynamicSettingsAttributes> => {
-    return {
-      id: '1',
-      type: 't',
-      references: [],
-      attributes: {
-        heartbeatIndices,
-        certAgeThreshold: 1,
-        certExpirationThreshold: 2,
-        defaultConnectors: ['example'],
-      },
-    };
-  };
-
-  it("adds the synthetics-* index if it's not in the indices settings", () => {
-    const doc = makeSettings('heartbeat-8*,something_else');
-    const result = add820Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'heartbeat-8*,something_else,synthetics-*',
-      },
-    });
-  });
-
-  it("adds the heartbeat-8* index if it's not in the indices settings", () => {
-    const doc = makeSettings('synthetics-*,something_else');
-    const result = add820Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'synthetics-*,something_else,heartbeat-8*',
-      },
-    });
-  });
-
-  it("adds both synthetics-* and heartbeat-8* index if they're not present in the indices", () => {
-    const doc = makeSettings('something-*,something_else');
-    const result = add820Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'something-*,something_else,synthetics-*,heartbeat-8*',
-      },
-    });
-  });
-
-  it('works for empty heartbeat indices fields', () => {
-    const doc = makeSettings('');
-    const result = add820Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'synthetics-*,heartbeat-8*',
-      },
-    });
-  });
-
-  it('works for undefined heartbeat indices fields', () => {
-    const doc = makeSettings('');
-
-    // We must TS ignore this so that we can delete this
-    // non-optional field and test that the migration still works
-    // when the field does not exist in the document
-    // @ts-expect-error
-    delete doc.attributes.heartbeatIndices;
-    const result = add820Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'synthetics-*,heartbeat-8*',
-      },
-    });
-  });
-});
-
-describe('remove890Indices migration', () => {
-  const context = { log: { warning: () => {} } } as unknown as SavedObjectMigrationContext;
-
-  const makeSettings = (heartbeatIndices: string): SavedObject<DynamicSettingsAttributes> => {
-    return {
-      id: '1',
-      type: 't',
-      references: [],
-      attributes: {
-        heartbeatIndices,
-        certAgeThreshold: 1,
-        certExpirationThreshold: 2,
-        defaultConnectors: ['example'],
-      },
-    };
-  };
-
-  it("removes the synthetics-* index if it's in the indices settings", () => {
-    const doc = makeSettings('heartbeat-8*,synthetics-*,something_else');
-    const result = remove890Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'heartbeat-8*,something_else',
-      },
-    });
-  });
-
-  it("adds the heartbeat-8* index if it's not in the indices settings", () => {
-    const doc = makeSettings('synthetics-*,something_else');
-    const result = remove890Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'something_else,heartbeat-8*',
-      },
-    });
-  });
-
-  it('works for empty heartbeat indices fields', () => {
-    const doc = makeSettings('');
-    const result = remove890Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'heartbeat-8*',
-      },
-    });
-  });
-
-  it('works for undefined heartbeat indices fields', () => {
-    const doc = makeSettings('');
-
-    // We must TS ignore this so that we can delete this
-    // non-optional field and test that the migration still works
-    // when the field does not exist in the document
-    // @ts-expect-error
-    delete doc.attributes.heartbeatIndices;
-    const result = remove890Indices(doc, context);
-    expect(result).toEqual({
-      ...doc,
-      attributes: {
-        ...doc.attributes,
-        heartbeatIndices: 'heartbeat-8*',
-      },
-    });
-  });
-});
diff --git a/x-pack/plugins/synthetics/server/saved_objects/migrations.ts b/x-pack/plugins/synthetics/server/saved_objects/migrations.ts
deleted file mode 100644
index 2b7e15e37d83a..0000000000000
--- a/x-pack/plugins/synthetics/server/saved_objects/migrations.ts
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0; you may not use this file except in compliance with the Elastic License
- * 2.0.
- */
-
-import { SavedObjectMigrationFn } from '@kbn/core/server';
-import { DynamicSettingsAttributes } from '../runtime_types/settings';
-
-export const add820Indices: SavedObjectMigrationFn<
-  DynamicSettingsAttributes,
-  DynamicSettingsAttributes
-> = (doc) => {
-  const heartbeatIndices = doc.attributes?.heartbeatIndices;
-
-  const indicesArr = !heartbeatIndices ? [] : heartbeatIndices.split(',');
-
-  if (!indicesArr.includes('synthetics-*')) {
-    indicesArr.push('synthetics-*');
-  }
-
-  if (!indicesArr.includes('heartbeat-8*')) {
-    indicesArr.push('heartbeat-8*');
-  }
-
-  const migratedObj = {
-    ...doc,
-    attributes: {
-      ...doc.attributes,
-      heartbeatIndices: indicesArr.join(','),
-    },
-  };
-
-  return migratedObj;
-};
-
-export const remove890Indices: SavedObjectMigrationFn<
-  DynamicSettingsAttributes,
-  DynamicSettingsAttributes
-> = (doc) => {
-  const heartbeatIndices = doc.attributes?.heartbeatIndices;
-
-  const indicesArr = !heartbeatIndices ? [] : heartbeatIndices.split(',');
-
-  // remove synthetics-* from the array
-  const indexToRemove = indicesArr.indexOf('synthetics-*');
-  if (indexToRemove > -1) {
-    indicesArr.splice(indexToRemove, 1);
-  }
-
-  if (!indicesArr.includes('heartbeat-8*')) {
-    indicesArr.push('heartbeat-8*');
-  }
-
-  return {
-    ...doc,
-    attributes: {
-      ...doc.attributes,
-      heartbeatIndices: indicesArr.join(','),
-    },
-  };
-};
diff --git a/x-pack/plugins/synthetics/server/saved_objects/saved_objects.ts b/x-pack/plugins/synthetics/server/saved_objects/saved_objects.ts
index 2ae631214e9e1..ae2ad1c712bc2 100644
--- a/x-pack/plugins/synthetics/server/saved_objects/saved_objects.ts
+++ b/x-pack/plugins/synthetics/server/saved_objects/saved_objects.ts
@@ -21,7 +21,7 @@ import { DYNAMIC_SETTINGS_DEFAULT_ATTRIBUTES } from '../constants/settings';
 import { DynamicSettingsAttributes } from '../runtime_types/settings';
 import { ConfigKey } from '../../common/runtime_types';
 import { UptimeConfig } from '../../common/config';
-import { settingsObjectId, umDynamicSettings } from './uptime_settings';
+import { settingsObjectId, settingsObjectType } from './uptime_settings';
 import {
   getSyntheticsMonitorSavedObjectType,
   SYNTHETICS_MONITOR_ENCRYPTED_TYPE,
@@ -63,10 +63,7 @@ export const savedObjectsAdapter: UMSavedObjectsAdapter = {
   config: null,
   getUptimeDynamicSettings: async (client) => {
     try {
-      const obj = await client.get<DynamicSettingsAttributes>(
-        umDynamicSettings.name,
-        settingsObjectId
-      );
+      const obj = await client.get<DynamicSettingsAttributes>(settingsObjectType, settingsObjectId);
       return obj?.attributes ?? DYNAMIC_SETTINGS_DEFAULT_ATTRIBUTES;
     } catch (getErr) {
       const config = savedObjectsAdapter.config;
@@ -80,7 +77,7 @@ export const savedObjectsAdapter: UMSavedObjectsAdapter = {
     }
   },
   setUptimeDynamicSettings: async (client, settings: DynamicSettingsAttributes | undefined) => {
-    await client.create(umDynamicSettings.name, settings, {
+    await client.create(settingsObjectType, settings, {
       id: settingsObjectId,
       overwrite: true,
     });
diff --git a/x-pack/plugins/synthetics/server/saved_objects/uptime_settings.ts b/x-pack/plugins/synthetics/server/saved_objects/uptime_settings.ts
index 7e6d94c3b4ebd..93cde59a25369 100644
--- a/x-pack/plugins/synthetics/server/saved_objects/uptime_settings.ts
+++ b/x-pack/plugins/synthetics/server/saved_objects/uptime_settings.ts
@@ -5,49 +5,5 @@
  * 2.0.
  */
 
-import { SavedObjectsType } from '@kbn/core/server';
-import { i18n } from '@kbn/i18n';
-import { add820Indices, remove890Indices } from './migrations';
-
 export const settingsObjectType = 'uptime-dynamic-settings';
 export const settingsObjectId = 'uptime-dynamic-settings-singleton';
-
-export const umDynamicSettings: SavedObjectsType = {
-  name: settingsObjectType,
-  hidden: false,
-  namespaceType: 'single',
-  mappings: {
-    dynamic: false,
-    properties: {
-      /* Leaving these commented to make it clear that these fields exist, even though we don't want them indexed.
-         When adding new fields please add them here. If they need to be searchable put them in the uncommented
-         part of properties.
-      heartbeatIndices: {
-        type: 'keyword',
-      },
-      certAgeThreshold: {
-        type: 'long',
-      },
-      certExpirationThreshold: {
-        type: 'long',
-      },
-      defaultConnectors: {
-        type: 'keyword',
-      },
-      */
-    },
-  },
-  management: {
-    importableAndExportable: true,
-    icon: 'uptimeApp',
-    getTitle: () =>
-      i18n.translate('xpack.synthetics.uptimeSettings.index', {
-        defaultMessage: 'Uptime Settings - Index',
-      }),
-  },
-  migrations: {
-    // Takes a pre 8.2.0 doc, and converts it to 8.2.0
-    '8.2.0': add820Indices,
-    '8.9.0': remove890Indices,
-  },
-};
diff --git a/x-pack/plugins/translations/translations/fr-FR.json b/x-pack/plugins/translations/translations/fr-FR.json
index f3f5713ea7357..8d312cf306da9 100644
--- a/x-pack/plugins/translations/translations/fr-FR.json
+++ b/x-pack/plugins/translations/translations/fr-FR.json
@@ -36383,7 +36383,6 @@
     "xpack.synthetics.totalDuration.metrics": "Durée de l’étape",
     "xpack.synthetics.totalDuration.transferSize": "Taille du transfert",
     "xpack.synthetics.uptimeFeatureCatalogueTitle": "Uptime",
-    "xpack.synthetics.uptimeSettings.index": "Paramètres Uptime - Index",
     "xpack.synthetics.wait": "Attendre",
     "xpack.synthetics.waterfall.applyFilters.label": "Sélectionner un élément auquel appliquer le filtre",
     "xpack.synthetics.waterfall.applyFilters.message": "Cliquer pour ajouter ou retirer le filtre",
diff --git a/x-pack/plugins/translations/translations/ja-JP.json b/x-pack/plugins/translations/translations/ja-JP.json
index cf26f95341638..d9ca725bbd4dd 100644
--- a/x-pack/plugins/translations/translations/ja-JP.json
+++ b/x-pack/plugins/translations/translations/ja-JP.json
@@ -36368,7 +36368,6 @@
     "xpack.synthetics.totalDuration.metrics": "ステップ期間",
     "xpack.synthetics.totalDuration.transferSize": "転送サイズ",
     "xpack.synthetics.uptimeFeatureCatalogueTitle": "アップタイム",
-    "xpack.synthetics.uptimeSettings.index": "アップタイム設定 - インデックス",
     "xpack.synthetics.wait": "待機",
     "xpack.synthetics.waterfall.applyFilters.label": "フィルターを適用するアイテムを選択",
     "xpack.synthetics.waterfall.applyFilters.message": "クリックして、フィルターを追加または削除します",
diff --git a/x-pack/plugins/translations/translations/zh-CN.json b/x-pack/plugins/translations/translations/zh-CN.json
index 6f5b3e721c83d..a778e8193a149 100644
--- a/x-pack/plugins/translations/translations/zh-CN.json
+++ b/x-pack/plugins/translations/translations/zh-CN.json
@@ -36362,7 +36362,6 @@
     "xpack.synthetics.totalDuration.metrics": "步骤持续时间",
     "xpack.synthetics.totalDuration.transferSize": "传输大小",
     "xpack.synthetics.uptimeFeatureCatalogueTitle": "运行时间",
-    "xpack.synthetics.uptimeSettings.index": "Uptime 设置 - 索引",
     "xpack.synthetics.wait": "等待",
     "xpack.synthetics.waterfall.applyFilters.label": "选择要应用筛选的项目",
     "xpack.synthetics.waterfall.applyFilters.message": "单击以添加或移除筛选",
diff --git a/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/duration_anomaly.ts b/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/duration_anomaly.ts
index 1ee03a5976ea8..a378f2d2a7fc5 100644
--- a/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/duration_anomaly.ts
+++ b/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/duration_anomaly.ts
@@ -142,7 +142,10 @@ export const durationAnomalyAlertFactory: UptimeAlertTypeFactory<ActionGroupIds>
   }) {
     const uptimeEsClient = new UptimeEsClient(
       savedObjectsClient,
-      scopedClusterClient.asCurrentUser
+      scopedClusterClient.asCurrentUser,
+      {
+        isLegacyAlert: true,
+      }
     );
     const { share, basePath } = server;
     const alertsLocator: LocatorPublic<AlertsLocatorParams> | undefined =
diff --git a/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/status_check.ts b/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/status_check.ts
index e9afea1504d97..dd713718a2c12 100644
--- a/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/status_check.ts
+++ b/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/status_check.ts
@@ -377,7 +377,10 @@ export const statusCheckAlertFactory: UptimeAlertTypeFactory<ActionGroupIds> = (
       share.url.locators.get(alertsLocatorID);
     const uptimeEsClient = new UptimeEsClient(
       savedObjectsClient,
-      scopedClusterClient.asCurrentUser
+      scopedClusterClient.asCurrentUser,
+      {
+        isLegacyAlert: true,
+      }
     );
 
     const filterString = await formatFilterString(uptimeEsClient, filters, search, libs);
diff --git a/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/tls.ts b/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/tls.ts
index 11c274feca20f..eb40a709174e7 100644
--- a/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/tls.ts
+++ b/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/tls.ts
@@ -155,6 +155,7 @@ export const tlsAlertFactory: UptimeAlertTypeFactory<ActionGroupIds> = (
     spaceId,
     startedAt,
     state,
+    rule,
   }) {
     const { share, basePath } = _server;
     const alertsLocator: LocatorPublic<AlertsLocatorParams> | undefined =
@@ -163,7 +164,10 @@ export const tlsAlertFactory: UptimeAlertTypeFactory<ActionGroupIds> = (
 
     const uptimeEsClient = new UptimeEsClient(
       savedObjectsClient,
-      scopedClusterClient.asCurrentUser
+      scopedClusterClient.asCurrentUser,
+      {
+        isLegacyAlert: true,
+      }
     );
 
     const certExpirationThreshold =
diff --git a/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/tls_legacy.ts b/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/tls_legacy.ts
index addb2dbbbdbe6..871157229b0a3 100644
--- a/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/tls_legacy.ts
+++ b/x-pack/plugins/uptime/server/legacy_uptime/lib/alerts/tls_legacy.ts
@@ -117,7 +117,10 @@ export const tlsLegacyAlertFactory: UptimeAlertTypeFactory<ActionGroupIds> = (_s
 
     const uptimeEsClient = new UptimeEsClient(
       savedObjectsClient,
-      scopedClusterClient.asCurrentUser
+      scopedClusterClient.asCurrentUser,
+      {
+        isLegacyAlert: true,
+      }
     );
     const { certs, total }: CertResult = await libs.requests.getCerts({
       uptimeEsClient,
diff --git a/x-pack/plugins/uptime/server/legacy_uptime/lib/lib.test.ts b/x-pack/plugins/uptime/server/legacy_uptime/lib/lib.test.ts
new file mode 100644
index 0000000000000..13a151da2e635
--- /dev/null
+++ b/x-pack/plugins/uptime/server/legacy_uptime/lib/lib.test.ts
@@ -0,0 +1,176 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { UptimeEsClient } from './lib';
+import { savedObjectsClientMock, uiSettingsServiceMock } from '@kbn/core/server/mocks';
+import { elasticsearchClientMock } from '@kbn/core-elasticsearch-client-server-mocks';
+import { savedObjectsAdapter } from './saved_objects';
+
+describe('UptimeEsClient', () => {
+  let uptimeEsClient: UptimeEsClient;
+  const savedObjectsClient = savedObjectsClientMock.create();
+  const esClient = elasticsearchClientMock.createClusterClient().asInternalUser;
+
+  beforeEach(() => {
+    uptimeEsClient = new UptimeEsClient(savedObjectsClient, esClient);
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  describe('search', () => {
+    it('should call baseESClient.search with correct parameters', async () => {
+      const mockSearchParams = {
+        body: {
+          query: {
+            match_all: {},
+          },
+        },
+      };
+
+      const result = await uptimeEsClient.search({
+        body: {
+          query: {
+            match_all: {},
+          },
+        },
+      });
+
+      expect(esClient.search).toHaveBeenCalledWith(
+        {
+          index: 'heartbeat-8*,heartbeat-7*',
+          ...mockSearchParams,
+        },
+        { meta: true }
+      );
+      expect(result).toEqual({
+        body: {},
+        headers: {
+          'x-elastic-product': 'Elasticsearch',
+        },
+        meta: {},
+        statusCode: 200,
+        warnings: [],
+      });
+    });
+
+    it('should throw an error if baseESClient.search throws an error', async () => {
+      const mockSearchParams = {
+        body: {
+          query: {
+            match_all: {},
+          },
+        },
+      };
+      const mockError = new Error('Search error');
+      esClient.search.mockRejectedValueOnce(mockError);
+
+      await expect(uptimeEsClient.search(mockSearchParams)).rejects.toThrow(mockError);
+      expect(esClient.search).toHaveBeenCalledWith(
+        {
+          index: 'heartbeat-8*,heartbeat-7*',
+          ...mockSearchParams,
+        },
+        { meta: true }
+      );
+    });
+  });
+
+  describe('count', () => {
+    it('should call baseESClient.count with correct parameters', async () => {
+      const mockCountParams = {
+        index: 'example',
+      };
+
+      const result = await uptimeEsClient.count(mockCountParams);
+
+      expect(esClient.count).toHaveBeenCalledWith(mockCountParams, { meta: true });
+      expect(result).toEqual({
+        indices: 'heartbeat-8*,heartbeat-7*',
+        result: {
+          body: {},
+          headers: {
+            'x-elastic-product': 'Elasticsearch',
+          },
+          meta: {},
+          statusCode: 200,
+          warnings: [],
+        },
+      });
+    });
+
+    it('should throw an error if baseESClient.count throws an error', async () => {
+      const mockCountParams = {
+        index: 'example',
+      };
+      const mockError = new Error('Count error');
+      esClient.count.mockRejectedValueOnce(mockError);
+
+      await expect(uptimeEsClient.count(mockCountParams)).rejects.toThrow(mockError);
+      expect(esClient.count).toHaveBeenCalledWith(mockCountParams, { meta: true });
+    });
+  });
+
+  describe('getInspectEnabled', () => {
+    it('should return false if uiSettings is not available', async () => {
+      const result = await uptimeEsClient.getInspectEnabled();
+
+      expect(result).toBe(false);
+    });
+
+    it('should return the value from uiSettings if available', async () => {
+      const mockUiSettings = uiSettingsServiceMock.createClient();
+      uptimeEsClient.uiSettings = {
+        client: mockUiSettings,
+      } as any;
+
+      // @ts-expect-error
+      mockUiSettings.get.mockReturnValue(true);
+
+      await uptimeEsClient.getInspectEnabled();
+
+      expect(uptimeEsClient.isInspectorEnabled).toBe(true);
+      expect(mockUiSettings.get).toHaveBeenCalledWith('observability:enableInspectEsQueries');
+    });
+  });
+  describe('heartbeatIndices', () => {
+    it('appends synthetics-* in index for legacy alerts', async () => {
+      savedObjectsAdapter.getUptimeDynamicSettings = jest.fn().mockResolvedValue({
+        heartbeatIndices: 'heartbeat-8*,heartbeat-7*',
+        syntheticsIndexRemoved: true,
+      });
+      uptimeEsClient = new UptimeEsClient(savedObjectsClient, esClient, { isLegacyAlert: true });
+
+      const mockSearchParams = {
+        body: {
+          query: {
+            match_all: {},
+          },
+        },
+      };
+
+      await uptimeEsClient.search({
+        body: {
+          query: {
+            match_all: {},
+          },
+        },
+      });
+
+      expect(esClient.search).toHaveBeenCalledWith(
+        {
+          index: 'heartbeat-8*,heartbeat-7*,synthetics-*',
+          ...mockSearchParams,
+        },
+        { meta: true }
+      );
+    });
+  });
+
+  // Add more tests for other methods and edge cases
+});
diff --git a/x-pack/plugins/uptime/server/legacy_uptime/lib/lib.ts b/x-pack/plugins/uptime/server/legacy_uptime/lib/lib.ts
index 8880e809861a4..e00104974014f 100644
--- a/x-pack/plugins/uptime/server/legacy_uptime/lib/lib.ts
+++ b/x-pack/plugins/uptime/server/legacy_uptime/lib/lib.ts
@@ -20,15 +20,8 @@ import { enableInspectEsQueries } from '@kbn/observability-plugin/common';
 import { getInspectResponse } from '@kbn/observability-shared-plugin/common';
 import { API_URLS } from '../../../common/constants';
 import { UptimeServerSetup } from './adapters';
-import { UMLicenseCheck } from './domains';
-import { UptimeRequests } from './requests';
 import { savedObjectsAdapter } from './saved_objects/saved_objects';
 
-export interface UMDomainLibs {
-  requests: UptimeRequests;
-  license: UMLicenseCheck;
-}
-
 export type { UMServerLibs } from '../uptime_server';
 
 export interface CountResponse {
@@ -55,6 +48,7 @@ export class UptimeEsClient {
   inspectableEsQueries: InspectResponse = [];
   uiSettings?: CoreRequestHandlerContext['uiSettings'];
   savedObjectsClient: SavedObjectsClientContract;
+  isLegacyAlert?: boolean;
 
   constructor(
     savedObjectsClient: SavedObjectsClientContract,
@@ -64,9 +58,17 @@ export class UptimeEsClient {
       uiSettings?: CoreRequestHandlerContext['uiSettings'];
       request?: KibanaRequest;
       heartbeatIndices?: string;
+      isLegacyAlert?: boolean;
     }
   ) {
-    const { isDev = false, uiSettings, request, heartbeatIndices = '' } = options ?? {};
+    const {
+      isLegacyAlert,
+      isDev = false,
+      uiSettings,
+      request,
+      heartbeatIndices = '',
+    } = options ?? {};
+    this.isLegacyAlert = isLegacyAlert;
     this.uiSettings = uiSettings;
     this.baseESClient = esClient;
     this.savedObjectsClient = savedObjectsClient;
@@ -197,11 +199,20 @@ export class UptimeEsClient {
   }
 
   async getIndices() {
+    // if isLegacyAlert appends synthetics-* if it's not already there
+    let indices = '';
+    let syntheticsIndexRemoved = false;
     if (this.heartbeatIndices) {
-      return this.heartbeatIndices;
+      indices = this.heartbeatIndices;
+    } else {
+      const settings = await savedObjectsAdapter.getUptimeDynamicSettings(this.savedObjectsClient);
+      indices = settings?.heartbeatIndices || '';
+      syntheticsIndexRemoved = settings.syntheticsIndexRemoved ?? false;
+    }
+    if (this.isLegacyAlert && !indices.includes('synthetics-') && syntheticsIndexRemoved) {
+      indices = indices + ',synthetics-*';
     }
-    const settings = await savedObjectsAdapter.getUptimeDynamicSettings(this.savedObjectsClient);
-    return settings?.heartbeatIndices || '';
+    return indices;
   }
 }
 
diff --git a/x-pack/plugins/uptime/server/legacy_uptime/lib/saved_objects/migrations.test.ts b/x-pack/plugins/uptime/server/legacy_uptime/lib/saved_objects/migrations.test.ts
index cccde17d79667..49c0a27b8be7d 100644
--- a/x-pack/plugins/uptime/server/legacy_uptime/lib/saved_objects/migrations.test.ts
+++ b/x-pack/plugins/uptime/server/legacy_uptime/lib/saved_objects/migrations.test.ts
@@ -117,6 +117,7 @@ describe('remove890Indices migration', () => {
       attributes: {
         ...doc.attributes,
         heartbeatIndices: 'heartbeat-8*,something_else',
+        syntheticsIndexRemoved: true,
       },
     });
   });
@@ -129,6 +130,7 @@ describe('remove890Indices migration', () => {
       attributes: {
         ...doc.attributes,
         heartbeatIndices: 'something_else,heartbeat-8*',
+        syntheticsIndexRemoved: true,
       },
     });
   });
diff --git a/x-pack/plugins/uptime/server/legacy_uptime/lib/saved_objects/migrations.ts b/x-pack/plugins/uptime/server/legacy_uptime/lib/saved_objects/migrations.ts
index 12ed237e1b569..45ae98a776daf 100644
--- a/x-pack/plugins/uptime/server/legacy_uptime/lib/saved_objects/migrations.ts
+++ b/x-pack/plugins/uptime/server/legacy_uptime/lib/saved_objects/migrations.ts
@@ -53,11 +53,14 @@ export const remove890Indices: SavedObjectMigrationFn<
     indicesArr.push('heartbeat-8*');
   }
 
+  const syntheticsIndexRemoved = indexToRemove > -1;
+
   return {
     ...doc,
     attributes: {
       ...doc.attributes,
       heartbeatIndices: indicesArr.join(','),
+      ...(syntheticsIndexRemoved && { syntheticsIndexRemoved }),
     },
   };
 };
diff --git a/x-pack/plugins/uptime/server/runtime_types/settings.ts b/x-pack/plugins/uptime/server/runtime_types/settings.ts
index 8f5ad64910558..152aced59fbb2 100644
--- a/x-pack/plugins/uptime/server/runtime_types/settings.ts
+++ b/x-pack/plugins/uptime/server/runtime_types/settings.ts
@@ -26,6 +26,7 @@ export const DynamicSettingsAttributesCodec = t.intersection([
   }),
   t.partial({
     defaultEmail: DefaultEmailCodec,
+    syntheticsIndexRemoved: t.boolean,
   }),
 ]);