Question Grainy-looking games, only on 2k monitor ?

[KennyLee86]

My 2 k monitor works great. But seems to have this weird issue. I play a game, and the game window is little bit grainy. UNLESS I click off screen on another one of my 2 monitors then it goes fine. (1080p monitors) (Trying to play some games with a controller I have to off click screen, so controller works) But some games still have a faint look of like shadows behind moving objects. Could it be partial refresh rate issues? or something?

i have a 4090
z790-a motherboard wifi
i9-13900 k 13th gen cpu
32gb ram