I’m experiencing this too (or at least something similar): my mouse cursor sort of hitches, resisting going in whatever direction it was previously moving. It’s maddening. I’ve tried every suggestion I can find online. I started with disabling all my addons, then deleting the WTF folder entirely. Nothing works, and it only happens in this game.
For reference, my issue seems identical to the one described here: FIXED | Mouse Cursor Sticks With Video Proof
The OP in that link says his issue was fixed with a patch back in 2020, but this only started happening to me this past week.