This DEV-only field was added in 836331ba5f69f2cc53b273ec073fae116db14302 by @sebmarkbage but it's not being used anymore to my knowledge.
HostPortal,
  ForwardRef,
  Fragment,
  Mode,
  ContextProvider,
  ContextConsumer,
  Profiler,
  SuspenseComponent,
  SuspenseListComponent,
  MemoComponent,
  SimpleMemoComponent,
  LazyComponent,
  IncompleteClassComponent,
  ScopeComponent,
  OffscreenComponent,
  LegacyHiddenComponent,
  CacheComponent,
} from './ReactWorkTags';
import {
  NoFlags,
  PerformedWork,
  Placement,
  Hydrating,
  ContentReset,
  DidCapture,
  Update,
  Ref,
  RefStatic,
  ChildDeletion,
  ForceUpdateForLegacySuspense,