OSS feature flag updates (#21597)

Co-authored-by: Dan Abramov <[email protected]>

Author: Brian Vaughn

packages/shared/ReactFeatureFlags.js

@@ -25,7 +25,7 @@ export const debugRenderPhaseSideEffectsForStrictMode = __DEV__;
 
 // Helps identify code that is not safe for planned Offscreen API and Suspense semantics;
 // this feature flag only impacts StrictEffectsMode.
-export const enableStrictEffects = false;
+export const enableStrictEffects = __DEV__;
 
 // If TRUE, trees rendered with createRoot will be StrictEffectsMode.
 // If FALSE, these trees will be StrictLegacyMode.
@@ -128,7 +128,7 @@ export const deletedTreeCleanUpLevel = 1;
 // Destroy layout effects for components that are hidden because something suspended in an update
 // and recreate them when they are shown again (after the suspended boundary has resolved).
 // Note that this should be an uncommon use case and can be avoided by using the transition API.
-export const enableSuspenseLayoutEffectSemantics = false;
+export const enableSuspenseLayoutEffectSemantics = true;
 
 // --------------------------
 // Future APIs to be deprecated

packages/shared/forks/ReactFeatureFlags.www.js

@@ -25,7 +25,6 @@ export const {
   deferRenderPhaseUpdateToNextBatch,
   enableDebugTracing,
   skipUnmountedBoundaries,
-  enableStrictEffects,
   createRootStrictEffectsByDefault,
   enableSuspenseLayoutEffectSemantics,
   enableUseRefAccessWarning,
@@ -39,6 +38,8 @@ export const {
 // On WWW, __EXPERIMENTAL__ is used for a new modern build.
 // It's not used anywhere in production yet.
 
+export const enableStrictEffects =
+  __DEV__ && dynamicFeatureFlags.enableStrictEffects;
 export const debugRenderPhaseSideEffectsForStrictMode = __DEV__;
 export const enableProfilerTimer = __PROFILE__;
 export const enableProfilerCommitHooks = __PROFILE__;