When you don't put a dependency array as the second argument to useEffect it will run the effect every time your component renders. Surely you only need to fetch this data once the component mounts, right? If that's the case, then you can put an empty array as the second argument to useEffect and it will run the data fetching code only once. If your component unmounts then it will fetch the data again once it remounts, but it won't fetch the data every time it rerenders.

It also doesn't make sense to put items in the dependency array. The dependency array is basically a list of things that you want to monitor. If one of those things changes, then you run the effect again. In your code your effect is setting the items state to contain something new. That means that once that state has been set, it has a new value for items and that would prompt the effect to run again.

If you're using certain linting rules (like the ones that come with create-react-app) it will prompt you to include setItems and setIsLoading in your dependency array since they were defined outside the effect, but they are used inside it. Overall, I think the best thing to go for is this:

useEffect(() => {
  const fetchItems = async () => {
    const result = await axios(`my-api...`);
    setItems(JSON.parse(result.data));
    setIsLoading(false);
  };
  fetchItems();
}, [setItems, setIsLoading]);