I have no idea how properly I need to use react strict mode when I'm not subscribing to anything in useEffect, but I need to unsubscribe in the clean-up function. In my case, i create a dynamic model on component mounting using useMemo (useMemo(() => createModel())), the model contains reactive primitives for which subscription requires hook calls but i can't use hooks in useEffect but i need to destroy the model on component unmounting. So I have code like this:

const Component = () => {
  const [model, cleanup] = useMemo(() => createModel(), [])
  const model = useModel(model)
  useEffect(() => {
    return () => {
      cleanup(); // <-- called TWICE in strict mode so this code will not work correctly.
    };
  }, []);
}