This DEV-only field was added in 836331ba5f69f2cc53b273ec073fae116db14302 by @sebmarkbage but it's not being used anymore to my knowledge.
const revealOrder: SuspenseListRevealOrder = nextProps.revealOrder;
  const tailMode: SuspenseListTailMode = nextProps.tail;
  const newChildren = nextProps.children;
  validateRevealOrder(revealOrder);
  validateTailOptions(tailMode, revealOrder);
  validateSuspenseListChildren(newChildren, revealOrder);
  reconcileChildren(current, workInProgress, newChildren, renderLanes);
  let suspenseContext: SuspenseContext = suspenseStackCursor.current;
  const shouldForceFallback = hasSuspenseContext(
    suspenseContext,
    (ForceSuspenseFallback: SuspenseContext),
  );
  if (shouldForceFallback) {
    suspenseContext = setShallowSuspenseContext(
      suspenseContext,
      ForceSuspenseFallback,
    );
    workInProgress.flags |= DidCapture;
  } else {
    const didSuspendBefore =
      current !== null && (current.flags & DidCapture) !== NoFlags;
    if (didSuspendBefore) {
      
      
      
      propagateSuspenseContextChange(
        workInProgress,
        workInProgress.child,
        renderLanes,
      );