diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.new.js b/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
index 508dfca5da459..376a7c9670a4e 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
@@ -116,6 +116,7 @@ import {
   Snapshot,
   Callback,
   Passive,
+  PassiveUnmountPendingDev,
   Incomplete,
   HostEffectMask,
   Hydrating,
@@ -2310,6 +2311,15 @@ export function enqueuePendingPassiveHookEffectUnmount(
 ): void {
   if (runAllPassiveEffectDestroysBeforeCreates) {
     pendingPassiveHookEffectsUnmount.push(effect, fiber);
+    if (__DEV__) {
+      if (deferPassiveEffectCleanupDuringUnmount) {
+        fiber.effectTag |= PassiveUnmountPendingDev;
+        const alternate = fiber.alternate;
+        if (alternate !== null) {
+          alternate.effectTag |= PassiveUnmountPendingDev;
+        }
+      }
+    }
     if (!rootDoesHavePassiveEffects) {
       rootDoesHavePassiveEffects = true;
       scheduleCallback(NormalPriority, () => {
@@ -2372,6 +2382,17 @@ function flushPassiveEffectsImpl() {
       const fiber = ((unmountEffects[i + 1]: any): Fiber);
       const destroy = effect.destroy;
       effect.destroy = undefined;
+
+      if (__DEV__) {
+        if (deferPassiveEffectCleanupDuringUnmount) {
+          fiber.effectTag &= ~PassiveUnmountPendingDev;
+          const alternate = fiber.alternate;
+          if (alternate !== null) {
+            alternate.effectTag &= ~PassiveUnmountPendingDev;
+          }
+        }
+      }
+
       if (typeof destroy === 'function') {
         if (__DEV__) {
           setCurrentDebugFiberInDEV(fiber);
@@ -2851,7 +2872,7 @@ function warnAboutUpdateOnUnmountedFiberInDEV(fiber) {
     ) {
       // If there are pending passive effects unmounts for this Fiber,
       // we can assume that they would have prevented this update.
-      if (pendingPassiveHookEffectsUnmount.indexOf(fiber) >= 0) {
+      if ((fiber.effectTag & PassiveUnmountPendingDev) !== NoEffect) {
         return;
       }
     }
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.old.js b/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
index ff50b56d3a580..713bcc23f85f2 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
@@ -116,6 +116,7 @@ import {
   Snapshot,
   Callback,
   Passive,
+  PassiveUnmountPendingDev,
   Incomplete,
   HostEffectMask,
   Hydrating,
@@ -2329,6 +2330,15 @@ export function enqueuePendingPassiveHookEffectUnmount(
 ): void {
   if (runAllPassiveEffectDestroysBeforeCreates) {
     pendingPassiveHookEffectsUnmount.push(effect, fiber);
+    if (__DEV__) {
+      if (deferPassiveEffectCleanupDuringUnmount) {
+        fiber.effectTag |= PassiveUnmountPendingDev;
+        const alternate = fiber.alternate;
+        if (alternate !== null) {
+          alternate.effectTag |= PassiveUnmountPendingDev;
+        }
+      }
+    }
     if (!rootDoesHavePassiveEffects) {
       rootDoesHavePassiveEffects = true;
       scheduleCallback(NormalPriority, () => {
@@ -2391,6 +2401,17 @@ function flushPassiveEffectsImpl() {
       const fiber = ((unmountEffects[i + 1]: any): Fiber);
       const destroy = effect.destroy;
       effect.destroy = undefined;
+
+      if (__DEV__) {
+        if (deferPassiveEffectCleanupDuringUnmount) {
+          fiber.effectTag &= ~PassiveUnmountPendingDev;
+          const alternate = fiber.alternate;
+          if (alternate !== null) {
+            alternate.effectTag &= ~PassiveUnmountPendingDev;
+          }
+        }
+      }
+
       if (typeof destroy === 'function') {
         if (__DEV__) {
           setCurrentDebugFiberInDEV(fiber);
@@ -2873,7 +2894,7 @@ function warnAboutUpdateOnUnmountedFiberInDEV(fiber) {
     ) {
       // If there are pending passive effects unmounts for this Fiber,
       // we can assume that they would have prevented this update.
-      if (pendingPassiveHookEffectsUnmount.indexOf(fiber) >= 0) {
+      if ((fiber.effectTag & PassiveUnmountPendingDev) !== NoEffect) {
         return;
       }
     }
diff --git a/packages/react-reconciler/src/ReactSideEffectTags.js b/packages/react-reconciler/src/ReactSideEffectTags.js
index ad3f01ac4b939..162b860c19eb3 100644
--- a/packages/react-reconciler/src/ReactSideEffectTags.js
+++ b/packages/react-reconciler/src/ReactSideEffectTags.js
@@ -10,28 +10,29 @@
 export type SideEffectTag = number;
 
 // Don't change these two values. They're used by React Dev Tools.
-export const NoEffect = /*              */ 0b0000000000000;
-export const PerformedWork = /*         */ 0b0000000000001;
+export const NoEffect = /*                 */ 0b00000000000000;
+export const PerformedWork = /*            */ 0b00000000000001;
 
 // You can change the rest (and add more).
-export const Placement = /*             */ 0b0000000000010;
-export const Update = /*                */ 0b0000000000100;
-export const PlacementAndUpdate = /*    */ 0b0000000000110;
-export const Deletion = /*              */ 0b0000000001000;
-export const ContentReset = /*          */ 0b0000000010000;
-export const Callback = /*              */ 0b0000000100000;
-export const DidCapture = /*            */ 0b0000001000000;
-export const Ref = /*                   */ 0b0000010000000;
-export const Snapshot = /*              */ 0b0000100000000;
-export const Passive = /*               */ 0b0001000000000;
-export const Hydrating = /*             */ 0b0010000000000;
-export const HydratingAndUpdate = /*    */ 0b0010000000100;
+export const Placement = /*                */ 0b00000000000010;
+export const Update = /*                   */ 0b00000000000100;
+export const PlacementAndUpdate = /*       */ 0b00000000000110;
+export const Deletion = /*                 */ 0b00000000001000;
+export const ContentReset = /*             */ 0b00000000010000;
+export const Callback = /*                 */ 0b00000000100000;
+export const DidCapture = /*               */ 0b00000001000000;
+export const Ref = /*                      */ 0b00000010000000;
+export const Snapshot = /*                 */ 0b00000100000000;
+export const Passive = /*                  */ 0b00001000000000;
+export const PassiveUnmountPendingDev = /* */ 0b10000000000000;
+export const Hydrating = /*                */ 0b00010000000000;
+export const HydratingAndUpdate = /*       */ 0b00010000000100;
 
 // Passive & Update & Callback & Ref & Snapshot
-export const LifecycleEffectMask = /*   */ 0b0001110100100;
+export const LifecycleEffectMask = /*      */ 0b00001110100100;
 
 // Union of all host effects
-export const HostEffectMask = /*        */ 0b0011111111111;
+export const HostEffectMask = /*           */ 0b00011111111111;
 
-export const Incomplete = /*            */ 0b0100000000000;
-export const ShouldCapture = /*         */ 0b1000000000000;
+export const Incomplete = /*               */ 0b00100000000000;
+export const ShouldCapture = /*            */ 0b01000000000000;
diff --git a/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js b/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js
index ff7a695fdca8d..424dc60946ac5 100644
--- a/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js
@@ -1252,6 +1252,95 @@ describe('ReactHooksWithNoopRenderer', () => {
       });
     });
 
+    // @gate deferPassiveEffectCleanupDuringUnmount && runAllPassiveEffectDestroysBeforeCreates
+    it('does not warn about state updates for unmounted components with pending passive unmounts for alternates', () => {
+      let setParentState = null;
+      const setChildStates = [];
+
+      function Parent() {
+        const [state, setState] = useState(true);
+        setParentState = setState;
+        Scheduler.unstable_yieldValue(`Parent ${state} render`);
+        useLayoutEffect(() => {
+          Scheduler.unstable_yieldValue(`Parent ${state} commit`);
+        });
+        if (state) {
+          return (
+            <>
+              <Child label="one" />
+              <Child label="two" />
+            </>
+          );
+        } else {
+          return null;
+        }
+      }
+
+      function Child({label}) {
+        const [state, setState] = useState(0);
+        useLayoutEffect(() => {
+          Scheduler.unstable_yieldValue(`Child ${label} commit`);
+        });
+        useEffect(() => {
+          setChildStates.push(setState);
+          Scheduler.unstable_yieldValue(`Child ${label} passive create`);
+          return () => {
+            Scheduler.unstable_yieldValue(`Child ${label} passive destroy`);
+          };
+        }, []);
+        Scheduler.unstable_yieldValue(`Child ${label} render`);
+        return state;
+      }
+
+      // Schedule debounced state update for child (prob a no-op for this test)
+      // later tick: schedule unmount for parent
+      // start process unmount (but don't flush passive effectS)
+      // State update on child
+      act(() => {
+        ReactNoop.render(<Parent />);
+        expect(Scheduler).toFlushAndYieldThrough([
+          'Parent true render',
+          'Child one render',
+          'Child two render',
+          'Child one commit',
+          'Child two commit',
+          'Parent true commit',
+          'Child one passive create',
+          'Child two passive create',
+        ]);
+
+        // Update children.
+        setChildStates.forEach(setChildState => setChildState(1));
+        expect(Scheduler).toFlushAndYieldThrough([
+          'Child one render',
+          'Child two render',
+          'Child one commit',
+          'Child two commit',
+        ]);
+
+        // Schedule another update for children, and partially process it.
+        setChildStates.forEach(setChildState => setChildState(2));
+        expect(Scheduler).toFlushAndYieldThrough(['Child one render']);
+
+        // Schedule unmount for the parent that unmounts children with pending update.
+        Scheduler.unstable_runWithPriority(
+          Scheduler.unstable_UserBlockingPriority,
+          () => setParentState(false),
+        );
+        expect(Scheduler).toFlushAndYieldThrough([
+          'Parent false render',
+          'Parent false commit',
+        ]);
+
+        // Schedule updates for children too (which should be ignored)
+        setChildStates.forEach(setChildState => setChildState(2));
+        expect(Scheduler).toFlushAndYield([
+          'Child one passive destroy',
+          'Child two passive destroy',
+        ]);
+      });
+    });
+
     it('warns about state updates for unmounted components with no pending passive unmounts', () => {
       let completePendingRequest = null;
       function Component() {