Busted GSync/VRR most certainly can present itself as perceived or actual stutter, sluggish mouse while controller is fine. Mice use mouse hid class and in raw input games are Hopefully unfiltered to stay true. Game controllers on the other hand get processed through direct input and are heavily filtered velocity based controls. Which is why they will generally be seen as smoother.
Not trying to argue with you but I think it's a tad naive to believe busted VRR couldn't be causing stutter. Fixed framerate only works if you can maintain fps that matches your displays hz...anything lower and thats why you need gsync. so let's say your system only puts out 105 fps on a 144hz monitor...fixed framerate will look horrible and even probably worse than a busted gsync implementation.
I get it doesn't work for you and that sucks...wished it did. All I can say is my mouse stutter yet smooth controller problem is now at least playable. :-D
For me I am sticking to roller till they address this.
My Freesync / Gsync is now 100% operational, works in its intended range with a flat frametime graph. No other game has this issue. :'D
Edit: additionally, gsync only affects input display. Not the input... input so to speak. So it does not get in the way of the mouse and the program. Just the monitor side. This why I claim that this issue is not strictly related to VRR. Controller input, while going through a dll, should suffer from the same issue, if VRR interfering was the case.
