Even if that's the case, max_user_watches is never less than 8k unless you've set it lower for some reason. If the editor is prioritizing currently open files as it should, there should basically never be a problem even if project sync suffers.
I just checked my workstation and found Watchman alone holds ~556K watches across 34 roots. It keeps those watches even after the tool that spawned it disconnects. Notably, I've never invoked Watchman manually -- other tools do. And the 8k floor isn't much of a floor. My nixpkgs checkout alone is 37,686 directories, 4.6x that.
Truthfully, I had no idea Watchman stays resident and accumulates watched roots. But, that's kind of the point. It's a very easy thing to miss.