Something weird as hell and I already checked it long time ago, Ferrites on the PCIE cables. this one is strange, I can see 100% improvement and feel the electricity through the cable and the ferrites when I put them on the PCIE, also, I can hear the noise changing, I did notice when the noise changes, becomes weaker or stronger, the mouse movement and input is changing, it happens really fast. So I think our main issue is noise coming to the PCIE cables no matter what it is and give us weird display issues. This is actually the MAIN ISSUE here, now what causing it is many many things, I can suggest you put the Ferrites on your 2 PCIE power cables that connects to your GPU and check, make sure it's really to it's last bit of space of the cable, or else you'll get some pretty weird noises and coil whining which actually affect my body, I start to feel really bad if I let the noises on the wrong position stay for long the higher the FPS the higher the noise, I can't explain what I feel but it's like you get electric shock through the air, and makes headacks. you can call it "electric through the air" which I can also feel if I touch the ferrite and move it around the farther from the last bit of the connector that plugged to the GPU. if we do 1+1 NOISE/EMI/DEVICES + PCIE Power Cabels (xLOAD) = Issues, we need to margin the PCIE power cables or the Devices outside, you could do even both to get the best quality of everything, if you don't do both I guess you'll have left overs of issues of display or some input lag.
I really really gave you the last answer in the straw, all you have to do is try it. I just tried Zombie Army 4 with unlimited fps reached to 500 fps in the menus and 170 in-game with 6900xt and i12700k P5.1 E4.0 and the mouse was damn fast and responsive, it was just as I had long time ago.
The mouse is actually faster than what you see on the video because one it's 120Hz TV and second I really need better camera to show you exactly how it moves. but what's important is it's accurate
What I learned in life, repeat the mistakes and you'll eventually learn, if you don't, you'll be stuck in the same position.
I uploaded 2 videos, one from a game and one shows just the movement
This video is old but shows where I put the Ferrites