https://codesandbox.io/s/upbeat-frost-3tt25

1. Press Suspend, see "Loading..."
2. Wait five seconds, you'll see "Happy birthday" at some point 
3. You won't see it again no matter how long you wait

Expected: you'll see it every five seconds.
if (
      current === null ||
      (current.memoizedState: null | SuspenseState) !== null
    ) {
      
      
      
      
      
      if (
        nextProps.fallback !== undefined &&
        nextProps.unstable_avoidThisFallback !== true
      ) {
        suspenseContext = addSubtreeSuspenseContext(
          suspenseContext,
          InvisibleParentSuspenseContext,
        );
      }
    }
  }
  suspenseContext = setDefaultShallowSuspenseContext(suspenseContext);
  pushSuspenseContext(workInProgress, suspenseContext);