First, there's the really nasty ones saying "If you ever work here, you can't work for any competitor for X years", and they're clearly abusing of employees, labor, etc. I hope there is a straight up ban on that.
The second kind is "You can't compete with us while you work here". And that is a much more complex beast. Obviously, if I work as a developer making a stock trading app, I shouldn't be making a competing stock trading app after hours.
But my employer does everything. There is no field that my employer is not involved in, somehow. You can guess who they are, probably, or just read my profile. And they say "You cannot do anything that competes with anything we do". Which is everything. Want to make a Sudoku app? That's a game, we do games. Want to do some open source ML library work? We do ML, you can't do ML outside of work (I asked legal that one). And that's ignoring the who-knows-how-many secret un-released projects that might relate.
They don't even tell us "no" anymore. They just say "read the non-compete agreement and do what it says". Basically "do what you like, but if we ever feel like it wasn't right, you're fired and maybe sued".
And when I apply to other companies, they ask "do you have a github account?". No, I've been highly motivated not to.
Edit: eesh, this was a bit of a rant, wasn't it? Apologies for that. But maybe folks have ideas on what to do about it, apart from the obvious.