diff --git a/packages/react-reconciler/src/ReactFiberFlags.js b/packages/react-reconciler/src/ReactFiberFlags.js
index da8255c6e8d11..518abbee11050 100644
--- a/packages/react-reconciler/src/ReactFiberFlags.js
+++ b/packages/react-reconciler/src/ReactFiberFlags.js
@@ -12,48 +12,49 @@ import {enableCreateEventHandleAPI} from 'shared/ReactFeatureFlags';
 export type Flags = number;
 
 // Don't change these two values. They're used by React Dev Tools.
-export const NoFlags = /*                      */ 0b0000000000000000000;
-export const PerformedWork = /*                */ 0b0000000000000000001;
+export const NoFlags = /*                      */ 0b00000000000000000000;
+export const PerformedWork = /*                */ 0b00000000000000000001;
 
 // You can change the rest (and add more).
-export const Placement = /*                    */ 0b0000000000000000010;
-export const Update = /*                       */ 0b0000000000000000100;
-export const PlacementAndUpdate = /*           */ 0b0000000000000000110;
-export const Deletion = /*                     */ 0b0000000000000001000;
-export const ContentReset = /*                 */ 0b0000000000000010000;
-export const Callback = /*                     */ 0b0000000000000100000;
-export const DidCapture = /*                   */ 0b0000000000001000000;
-export const Ref = /*                          */ 0b0000000000010000000;
-export const Snapshot = /*                     */ 0b0000000000100000000;
-export const Passive = /*                      */ 0b0000000001000000000;
-export const Hydrating = /*                    */ 0b0000000010000000000;
-export const HydratingAndUpdate = /*           */ 0b0000000010000000100;
-export const Visibility = /*                   */ 0b0000000100000000000;
+export const Placement = /*                    */ 0b00000000000000000010;
+export const Update = /*                       */ 0b00000000000000000100;
+export const PlacementAndUpdate = /*           */ Placement | Update;
+export const Deletion = /*                     */ 0b00000000000000001000;
+export const ChildDeletion = /*                */ 0b00000000000000010000;
+export const ContentReset = /*                 */ 0b00000000000000100000;
+export const Callback = /*                     */ 0b00000000000001000000;
+export const DidCapture = /*                   */ 0b00000000000010000000;
+export const Ref = /*                          */ 0b00000000000100000000;
+export const Snapshot = /*                     */ 0b00000000001000000000;
+export const Passive = /*                      */ 0b00000000010000000000;
+export const Hydrating = /*                    */ 0b00000000100000000000;
+export const HydratingAndUpdate = /*           */ Hydrating | Update;
+export const Visibility = /*                   */ 0b00000001000000000000;
 
 export const LifecycleEffectMask = Passive | Update | Callback | Ref | Snapshot;
 
 // Union of all commit flags (flags with the lifetime of a particular commit)
-export const HostEffectMask = /*               */ 0b0000000111111111111;
+export const HostEffectMask = /*               */ 0b00000001111111111111;
 
 // These are not really side effects, but we still reuse this field.
-export const Incomplete = /*                   */ 0b0000001000000000000;
-export const ShouldCapture = /*                */ 0b0000010000000000000;
+export const Incomplete = /*                   */ 0b00000010000000000000;
+export const ShouldCapture = /*                */ 0b00000100000000000000;
 // TODO (effects) Remove this bit once the new reconciler is synced to the old.
-export const PassiveUnmountPendingDev = /*     */ 0b0000100000000000000;
-export const ForceUpdateForLegacySuspense = /* */ 0b0001000000000000000;
+export const PassiveUnmountPendingDev = /*     */ 0b00001000000000000000;
+export const ForceUpdateForLegacySuspense = /* */ 0b00010000000000000000;
 
 // Static tags describe aspects of a fiber that are not specific to a render,
 // e.g. a fiber uses a passive effect (even if there are no updates on this particular render).
 // This enables us to defer more work in the unmount case,
 // since we can defer traversing the tree during layout to look for Passive effects,
 // and instead rely on the static flag as a signal that there may be cleanup work.
-export const PassiveStatic = /*                */ 0b0010000000000000000;
+export const PassiveStatic = /*                */ 0b00100000000000000000;
 
 // These flags allow us to traverse to fibers that have effects on mount
 // without traversing the entire tree after every commit for
 // double invoking
-export const MountLayoutDev = /*               */ 0b0100000000000000000;
-export const MountPassiveDev = /*              */ 0b1000000000000000000;
+export const MountLayoutDev = /*               */ 0b01000000000000000000;
+export const MountPassiveDev = /*              */ 0b10000000000000000000;
 
 // Groups of flags that are used in the commit phase to skip over trees that
 // don't contain effects, by checking subtreeFlags.
@@ -65,13 +66,19 @@ export const BeforeMutationMask =
       // fire beforeblur
       // TODO: Only need to visit Deletions during BeforeMutation phase if an
       // element is focused.
-      Deletion | Visibility
+      ChildDeletion | Visibility
     : 0);
 
 export const MutationMask =
-  Placement | Update | Deletion | ContentReset | Ref | Hydrating | Visibility;
+  Placement |
+  Update |
+  ChildDeletion |
+  ContentReset |
+  Ref |
+  Hydrating |
+  Visibility;
 export const LayoutMask = Update | Callback | Ref;
-export const PassiveMask = Passive | Deletion;
+export const PassiveMask = Passive | ChildDeletion;
 
 // Union of tags that don't get reset on clones.
 // This allows certain concepts to persist without recalculting them,