Repro: https://codesandbox.io/s/fast-water-4i4jb

Notice the flash. I'd expect `suspended` to be `true` during the high pri render.
if (!supportsHydration) {
    return false;
  }
  const parentInstance = fiber.stateNode.containerInfo;
  nextHydratableInstance = getFirstHydratableChild(parentInstance);
  hydrationParentFiber = fiber;
  isHydrating = true;
  return true;
}
function reenterHydrationStateFromDehydratedSuspenseInstance(
  fiber: Fiber,
  suspenseInstance: SuspenseInstance,
): boolean {
  if (!supportsHydration) {
    return false;
  }
  nextHydratableInstance = getNextHydratableSibling(suspenseInstance);
  popToNextHostParent(fiber);
  isHydrating = true;
  return true;
}
function deleteHydratableInstance(
  returnFiber: Fiber,
  instance: HydratableInstance,
) {
  if (__DEV__) {
    switch (returnFiber.tag) {
      case HostRoot:
        didNotHydrateContainerInstance(
          returnFiber.stateNode.containerInfo,