What's the difference between these solutions when dealing with cleaning up of unmounted components? useRef vs boolean variable

Question

I've learned that to prevent memory leaks, I'm supposed to clean up after useEffect hooks which call async functions to update state.

I have found a couple of solutions for this;

First one, to use a simple, boolean variable:

useEffect(() => {
let isSubscribed = true;

const runEffect = async () => {
  const data = await getSomething();
  isSubscribed && setState(data)
};

runEffect();

return () => {
      isSubscribed = false;
    };
  }, []);

And this method using the useRef hook:

const _isMounted = useRef(true); 

  useEffect(() => {
const runEffect = async () => {
      const data = await getSomething();
      _isMounted.current && setState(data)
    };

    runEffect();

    return () => { 
        _isMounted.current = false;
    }
  }, []);

Is there a big enough difference between the two methods? If so, which is better?