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.
No classes, no mutable types, pure functions where possible (I/O functions exist). I like elixir myself. I use for loops or recursion depending on which is suitable and most understandable. I like the pipe operator because I've gotten used to chaining inputs and outputs like that from Linux CLI.
I prefer functional programming, but also use OO, each their own, but i prefer functional and find it better to write and read