Mine is that the useState hook is an actual plague on the entire React ecosystem. Regardless of your opinions of React, if you wanna use something then use it right.
if you're making a user-facing program, you should always design with the possibility that it will be run on some truly dogshit hardware and you should make sure that they still have a good experience. good computer hardware is a luxury on the world scale, even before the rampocalypse
related, but the answer to the question "who still uses {x} these days?" is almost always way, wayyyy more people than you think