// ❌ LEAK: Interval continues after unmount
function Component() {
  useEffect(() => {
    setInterval(() => {
      fetchData();
    }, 5000);
  }, []);
}

// ✅ CORRECT
function Component() {
  useEffect(() => {
    const interval = setInterval(() => {
      fetchData();
    }, 5000);
    return () => clearInterval(interval);
  }, []);
}

        __
        __