Stop Using useEffect Like This: 5 Patterns That Are Silently Breaking Your React App

I was doing a code review for a colleague when I found it. The component had five useEffect hooks. No errors. No warnings in the console. The PM had signed off on it. It had been in production for three months. But there was a subtle bug that only showed up when the user navigated quickly between pages. Data would flash. State would reset. Sometimes the old user's name would appear for a split second before updating to the new one. Three hours later, we traced it back to a single misused useEffe