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.
Zed sucks in many of the ways that modern editors suck.
Autocompleting on characters that appear in code, and autocompleting in a way that overwrites the code you have already written are two incredibly stupid decisions that put a mark over any tool that adopts any one of them.
But then, Zed almost working, but in a way that still sucks was enough to motivate me into setting my Emacs properly, in a way that doesn't suck. So Zed gave me a good editor.