Same here, experience got worse after upgrading the monitor.
I went from a somewhat matched pair of 1080p 75Hz monitors, one of which was ultrawide (2560 width) to upgrading my ultrawide to a 3440x1440 160hz panel.
That upgraded panel suffered every step of the way in Linux.
I absolutely cannot get 160Hz consistently if I have both monitors running. On KDE X11, compositor drops the rate to 75FPS to even things out (except the mouse lol). On KDE Wayland it works properly in this regard, but we all know how Wayland is on NVIDIA right now.
GNOME is a similar story as KDE Wayland, with an added bonus of stuttering.
I’m not losing hope, though. It’s gonna catch up to AMD but man does it stink to use lol
The only other reason I really have to use X11 is because the hardware video decoding in the browser doesn’t work in Wayland with NVIDIA. Most of the apps are actually becoming more and more stable.