In Windows are you using any mouse software or settings, like Mouse Trails? If so please set the cursor to the default Windows setting before starting the game.
I've seen reports of this with CSL on Epic only, no other game. My best guess is it relates to some change in the Epic client but I haven't been able to prove that.
@Jamface662 Unload the Epic client entirely then run EU4.exe by itself. Does this still happen?