React: useEffect runs twice in development

My useEffect with an empty dependency array fires twice on mount, so my analytics event is sent twice. Is my component mounting twice?

In development with Strict Mode, React mounts, unmounts and re-mounts every component once to surface effects that are missing a cleanup. It does not happen in production builds.

Write effects that are safe to run twice — return a cleanup, or guard side effects that must happen once (like analytics) outside the component.

Confirmed — production build only fires once.