This event is not triggered in the "same page" but in "another page". It's used for observing localStorage changes when a user opens multple tabs. It is not triggered when the value is not changed (in other words, `localStorage.setItem(KEY, VALUE)` doesn't fire the event when the VALUE is not changed.)
`useFormState` is also exported from `react-dom`. Are client only hooks exported from `react-dom` in future?