diff --git a/packages/react-reconciler/src/ReactFiberClassComponent.js b/packages/react-reconciler/src/ReactFiberClassComponent.js
index 9fd6d5dc3169d..e53885f900e96 100644
--- a/packages/react-reconciler/src/ReactFiberClassComponent.js
+++ b/packages/react-reconciler/src/ReactFiberClassComponent.js
@@ -23,7 +23,6 @@ import {
   disableLegacyContext,
   enableDebugTracing,
   enableSchedulingProfiler,
-  warnAboutDeprecatedLifecycles,
   enableLazyContextPropagation,
 } from 'shared/ReactFeatureFlags';
 import ReactStrictModeWarnings from './ReactStrictModeWarnings';
@@ -868,12 +867,10 @@ function mountClassInstance(
       );
     }
 
-    if (warnAboutDeprecatedLifecycles) {
-      ReactStrictModeWarnings.recordUnsafeLifecycleWarnings(
-        workInProgress,
-        instance,
-      );
-    }
+    ReactStrictModeWarnings.recordUnsafeLifecycleWarnings(
+      workInProgress,
+      instance,
+    );
   }
 
   instance.state = workInProgress.memoizedState;
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.js b/packages/react-reconciler/src/ReactFiberWorkLoop.js
index 7009380c1d963..a6637f4bcc41d 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.js
@@ -24,7 +24,6 @@ import type {
 import type {OffscreenInstance} from './ReactFiberOffscreenComponent';
 
 import {
-  warnAboutDeprecatedLifecycles,
   replayFailedUnitOfWorkWithInvokeGuardedCallback,
   enableCreateEventHandleAPI,
   enableProfilerTimer,
@@ -3534,10 +3533,7 @@ export function throwIfInfiniteUpdateLoopDetected() {
 function flushRenderPhaseStrictModeWarningsInDEV() {
   if (__DEV__) {
     ReactStrictModeWarnings.flushLegacyContextWarning();
-
-    if (warnAboutDeprecatedLifecycles) {
-      ReactStrictModeWarnings.flushPendingUnsafeLifecycleWarnings();
-    }
+    ReactStrictModeWarnings.flushPendingUnsafeLifecycleWarnings();
   }
 }
 
diff --git a/packages/react-server/src/ReactFizzClassComponent.js b/packages/react-server/src/ReactFizzClassComponent.js
index 599df4f6d1f97..44b3e50294855 100644
--- a/packages/react-server/src/ReactFizzClassComponent.js
+++ b/packages/react-server/src/ReactFizzClassComponent.js
@@ -10,10 +10,7 @@
 import {emptyContextObject} from './ReactFizzContext';
 import {readContext} from './ReactFizzNewContext';
 
-import {
-  disableLegacyContext,
-  warnAboutDeprecatedLifecycles,
-} from 'shared/ReactFeatureFlags';
+import {disableLegacyContext} from 'shared/ReactFeatureFlags';
 import {get as getInstance, set as setInstance} from 'shared/ReactInstanceMap';
 import getComponentNameFromType from 'shared/getComponentNameFromType';
 import {REACT_CONTEXT_TYPE, REACT_PROVIDER_TYPE} from 'shared/ReactSymbols';
@@ -539,10 +536,7 @@ function callComponentWillMount(type: any, instance: any) {
 
   if (typeof instance.componentWillMount === 'function') {
     if (__DEV__) {
-      if (
-        warnAboutDeprecatedLifecycles &&
-        instance.componentWillMount.__suppressDeprecationWarning !== true
-      ) {
+      if (instance.componentWillMount.__suppressDeprecationWarning !== true) {
         const componentName = getComponentNameFromType(type) || 'Unknown';
 
         if (!didWarnAboutDeprecatedWillMount[componentName]) {
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 24dc67d374692..dd01bb14e42de 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -13,7 +13,6 @@
 // Flags that can likely be deleted or landed without consequences
 // -----------------------------------------------------------------------------
 
-export const warnAboutDeprecatedLifecycles = true;
 export const enableComponentStackLocations = true;
 export const disableSchedulerTimeoutBasedOnReactExpirationTime = false;
 
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index c43847ff08df5..9fe2bdcfcd63a 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -37,7 +37,6 @@ export const disableJavaScriptURLs = false;
 export const disableCommentsAsDOMContainers = true;
 export const disableInputAttributeSyncing = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
-export const warnAboutDeprecatedLifecycles = true;
 export const enableScopeAPI = false;
 export const enableCreateEventHandleAPI = false;
 export const enableSuspenseCallback = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index 401362abc7f90..3d403ab509fbb 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -14,7 +14,6 @@ export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableDebugTracing = false;
 export const enableSchedulingProfiler = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
-export const warnAboutDeprecatedLifecycles = true;
 export const enableProfilerTimer = __PROFILE__;
 export const enableProfilerCommitHooks = __PROFILE__;
 export const enableProfilerNestedUpdatePhase = __PROFILE__;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index 96fd0dd2cca18..907351d7102c2 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -13,7 +13,6 @@ import typeof * as ExportsType from './ReactFeatureFlags.test-renderer';
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableDebugTracing = false;
 export const enableSchedulingProfiler = false;
-export const warnAboutDeprecatedLifecycles = true;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = __PROFILE__;
 export const enableProfilerCommitHooks = __PROFILE__;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
index bcdcd974509a8..34f467ab3012d 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
@@ -13,7 +13,6 @@ import typeof * as ExportsType from './ReactFeatureFlags.test-renderer';
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableDebugTracing = false;
 export const enableSchedulingProfiler = false;
-export const warnAboutDeprecatedLifecycles = true;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = __PROFILE__;
 export const enableProfilerCommitHooks = __PROFILE__;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index f2dcfc00f9b55..b7eecfaeef7a4 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -13,7 +13,6 @@ import typeof * as ExportsType from './ReactFeatureFlags.test-renderer.www';
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableDebugTracing = false;
 export const enableSchedulingProfiler = false;
-export const warnAboutDeprecatedLifecycles = true;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = __PROFILE__;
 export const enableProfilerCommitHooks = __PROFILE__;
diff --git a/packages/shared/forks/ReactFeatureFlags.testing.js b/packages/shared/forks/ReactFeatureFlags.testing.js
index 1dda88f6bc176..0f17f71b0d171 100644
--- a/packages/shared/forks/ReactFeatureFlags.testing.js
+++ b/packages/shared/forks/ReactFeatureFlags.testing.js
@@ -13,7 +13,6 @@ import typeof * as ExportsType from './ReactFeatureFlags.testing';
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableDebugTracing = false;
 export const enableSchedulingProfiler = __PROFILE__;
-export const warnAboutDeprecatedLifecycles = true;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = __PROFILE__;
 export const enableProfilerCommitHooks = __PROFILE__;
diff --git a/packages/shared/forks/ReactFeatureFlags.testing.www.js b/packages/shared/forks/ReactFeatureFlags.testing.www.js
index cd4535e761a10..bffb42bf78416 100644
--- a/packages/shared/forks/ReactFeatureFlags.testing.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.testing.www.js
@@ -13,7 +13,6 @@ import typeof * as ExportsType from './ReactFeatureFlags.testing.www';
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableDebugTracing = false;
 export const enableSchedulingProfiler = false;
-export const warnAboutDeprecatedLifecycles = true;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = false;
 export const enableProfilerCommitHooks = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index 73a592286cb88..6953f09aef1d5 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -65,7 +65,6 @@ export const enableSchedulingProfiler: boolean =
 // For now, we'll turn it on for everyone because it's *already* on for everyone in practice.
 // At least this will let us stop shipping <Profiler> implementation to all users.
 export const enableSchedulerDebugging = true;
-export const warnAboutDeprecatedLifecycles = true;
 export const disableLegacyContext = __EXPERIMENTAL__;
 export const warnAboutStringRefs = true;
 export const warnAboutDefaultPropsOnFunctionComponents = true;