This DEV-only field was added in 836331ba5f69f2cc53b273ec073fae116db14302 by @sebmarkbage but it's not being used anymore to my knowledge.
StrictLegacyMode,
} from './ReactTypeOfMode';
import {
  shouldSetTextContent,
  isSuspenseInstancePending,
  isSuspenseInstanceFallback,
  registerSuspenseInstanceRetry,
  supportsHydration,
  isPrimaryRenderer,
} from './ReactFiberHostConfig';
import type {SuspenseInstance} from './ReactFiberHostConfig';
import {shouldSuspend} from './ReactFiberReconciler';
import {pushHostContext, pushHostContainer} from './ReactFiberHostContext.old';
import {
  suspenseStackCursor,
  pushSuspenseContext,
  InvisibleParentSuspenseContext,
  ForceSuspenseFallback,
  hasSuspenseContext,
  setDefaultShallowSuspenseContext,
  addSubtreeSuspenseContext,
  setShallowSuspenseContext,
} from './ReactFiberSuspenseContext.old';
import {findFirstSuspended} from './ReactFiberSuspenseComponent.old';
import {
  pushProvider,
  propagateContextChange,
  lazilyPropagateParentContextChanges,
  propagateParentContextChangesToDeferredTree,
  checkIfContextChanged,