diff --git a/packages/eslint-config-sdk/src/index.js b/packages/eslint-config-sdk/src/index.js
index b93cc63508df..d09be9e2e67d 100644
--- a/packages/eslint-config-sdk/src/index.js
+++ b/packages/eslint-config-sdk/src/index.js
@@ -143,7 +143,10 @@ module.exports = {
           },
         ],
 
+        // We want to prevent optional chaining & nullish coalescing usage in our files
+        // to prevent uncessary bundle size. Turned off in tests.
         '@sentry-internal/sdk/no-optional-chaining': 'error',
+        '@sentry-internal/sdk/no-nullish-coalescing': 'error',
 
         // JSDOC comments are required for classes and methods. As we have a public facing codebase, documentation,
         // even if it may seems excessive at times, is important to emphasize. Turned off in tests.
@@ -177,6 +180,7 @@ module.exports = {
         '@typescript-eslint/no-non-null-assertion': 'off',
         '@typescript-eslint/no-empty-function': 'off',
         '@sentry-internal/sdk/no-optional-chaining': 'off',
+        '@sentry-internal/sdk/no-nullish-coalescing': 'off',
       },
     },
     {
diff --git a/packages/eslint-plugin-sdk/src/index.js b/packages/eslint-plugin-sdk/src/index.js
index 8b94bbe4705b..31ac785abf5e 100644
--- a/packages/eslint-plugin-sdk/src/index.js
+++ b/packages/eslint-plugin-sdk/src/index.js
@@ -11,6 +11,7 @@
 module.exports = {
   rules: {
     'no-optional-chaining': require('./rules/no-optional-chaining'),
+    'no-nullish-coalescing': require('./rules/no-nullish-coalescing'),
     'no-eq-empty': require('./rules/no-eq-empty'),
   },
 };
diff --git a/packages/eslint-plugin-sdk/src/rules/no-nullish-coalescing.js b/packages/eslint-plugin-sdk/src/rules/no-nullish-coalescing.js
new file mode 100644
index 000000000000..8944f2755632
--- /dev/null
+++ b/packages/eslint-plugin-sdk/src/rules/no-nullish-coalescing.js
@@ -0,0 +1,48 @@
+/**
+ * @fileoverview disallow nullish coalescing operators as they were introduced only in ES2020 and hence require
+ * us to add a polyfill. This increases bundle size more than avoiding nullish coalescing operators all together.
+ *
+ * @author Lukas Stracke
+ *
+ * Based on: https://github.com/mysticatea/eslint-plugin-es/blob/v4.1.0/lib/rules/no-nullish-coalescing-operators.js
+ */
+'use strict';
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'disallow nullish coalescing operators.',
+      category: 'Best Practices',
+      recommended: true,
+    },
+    messages: {
+      forbidden: 'Avoid using nullish coalescing operators.',
+    },
+    fixable: null,
+    schema: [],
+  },
+  create(context) {
+    return {
+      "LogicalExpression[operator='??']"(node) {
+        context.report({
+          node: context.getSourceCode().getTokenAfter(node.left, isNullishCoalescingOperator),
+          messageId: 'forbidden',
+        });
+      },
+    };
+  },
+};
+
+/**
+ * Checks if the given token is a nullish coalescing operator or not.
+ * @param {Token} token - The token to check.
+ * @returns {boolean} `true` if the token is a nullish coalescing operator.
+ */
+function isNullishCoalescingOperator(token) {
+  return token.value === '??' && token.type === 'Punctuator';
+}
diff --git a/packages/nextjs/.eslintrc.js b/packages/nextjs/.eslintrc.js
index b6f6b1b9938c..96c2b0d8e4a2 100644
--- a/packages/nextjs/.eslintrc.js
+++ b/packages/nextjs/.eslintrc.js
@@ -10,6 +10,7 @@ module.exports = {
   extends: ['../../.eslintrc.js'],
   rules: {
     '@sentry-internal/sdk/no-optional-chaining': 'off',
+    '@sentry-internal/sdk/no-nullish-coalescing': 'off',
   },
   overrides: [
     {
diff --git a/packages/node/.eslintrc.js b/packages/node/.eslintrc.js
index 9899ea1b73d8..e15b119aa31e 100644
--- a/packages/node/.eslintrc.js
+++ b/packages/node/.eslintrc.js
@@ -5,5 +5,6 @@ module.exports = {
   extends: ['../../.eslintrc.js'],
   rules: {
     '@sentry-internal/sdk/no-optional-chaining': 'off',
+    '@sentry-internal/sdk/no-nullish-coalescing': 'off',
   },
 };
diff --git a/packages/tracing/src/browser/browsertracing.ts b/packages/tracing/src/browser/browsertracing.ts
index 5fb1a81f0779..8502e5d1b13f 100644
--- a/packages/tracing/src/browser/browsertracing.ts
+++ b/packages/tracing/src/browser/browsertracing.ts
@@ -317,7 +317,7 @@ export class BrowserTracing implements Integration {
         op,
         trimEnd: true,
         metadata: {
-          source: this._latestRouteSource ?? 'url',
+          source: this._latestRouteSource || 'url',
         },
       };
 
diff --git a/packages/tracing/src/browser/metrics/index.ts b/packages/tracing/src/browser/metrics/index.ts
index 7bd575e90024..67cdc1714ed9 100644
--- a/packages/tracing/src/browser/metrics/index.ts
+++ b/packages/tracing/src/browser/metrics/index.ts
@@ -304,7 +304,7 @@ function _addPerformanceNavigationTiming(
   }
   _startChild(transaction, {
     op: 'browser',
-    description: description ?? event,
+    description: description || event,
     startTimestamp: timeOrigin + msToSec(start),
     endTimestamp: timeOrigin + msToSec(end),
   });
diff --git a/packages/tracing/src/span.ts b/packages/tracing/src/span.ts
index db11bb931df7..72f27721bb28 100644
--- a/packages/tracing/src/span.ts
+++ b/packages/tracing/src/span.ts
@@ -294,17 +294,17 @@ export class Span implements SpanInterface {
    * @inheritDoc
    */
   public updateWithContext(spanContext: SpanContext): this {
-    this.data = spanContext.data ?? {};
+    this.data = spanContext.data || {};
     this.description = spanContext.description;
     this.endTimestamp = spanContext.endTimestamp;
     this.op = spanContext.op;
     this.parentSpanId = spanContext.parentSpanId;
     this.sampled = spanContext.sampled;
-    this.spanId = spanContext.spanId ?? this.spanId;
-    this.startTimestamp = spanContext.startTimestamp ?? this.startTimestamp;
+    this.spanId = spanContext.spanId || this.spanId;
+    this.startTimestamp = spanContext.startTimestamp || this.startTimestamp;
     this.status = spanContext.status;
-    this.tags = spanContext.tags ?? {};
-    this.traceId = spanContext.traceId ?? this.traceId;
+    this.tags = spanContext.tags || {};
+    this.traceId = spanContext.traceId || this.traceId;
 
     return this;
   }
diff --git a/packages/tracing/src/transaction.ts b/packages/tracing/src/transaction.ts
index b93d52b81c38..5b32612302ee 100644
--- a/packages/tracing/src/transaction.ts
+++ b/packages/tracing/src/transaction.ts
@@ -238,7 +238,7 @@ export class Transaction extends SpanClass implements TransactionInterface {
   public updateWithContext(transactionContext: TransactionContext): this {
     super.updateWithContext(transactionContext);
 
-    this.name = transactionContext.name ?? '';
+    this.name = transactionContext.name || '';
 
     this._trimEnd = transactionContext.trimEnd;