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

Notice the flash. I'd expect `suspended` to be `true` during the high pri render.
prepareToReadContext(workInProgress, renderExpirationTime);
  constructClassInstance(workInProgress, Component, nextProps);
  mountClassInstance(
    workInProgress,
    Component,
    nextProps,
    renderExpirationTime,
  );
  return finishClassComponent(
    null,
    workInProgress,
    Component,
    true,
    hasContext,
    renderExpirationTime,
  );
}
function mountIndeterminateComponent(
  _current,
  workInProgress,
  Component,
  renderExpirationTime,
) {
  if (_current !== null) {
    
    
    
    
    _current.alternate = null;
    workInProgress.alternate = null;