Same here, running a pair of 1440p monitors off my Hades Canyon NUC, running Kubuntu 20.04.

Largely now without tweaks, but it needed some when I originally got it to use Kisak-mesa.

neofetch output: OS: Ubuntu 20.04 LTS x86_64 Host: NUC8i7HVK (REMOVED) Kernel: 5.4.0-42-generic Uptime: 5 hours, 7 mins Packages: 3266 (dpkg), 7 (snap) Shell: bash 5.0.17 Resolution: 2560x1440, 2560x1440 DE: Plasma WM: KWin Theme: Breeze [Plasma], Breeze [GTK2/3] Icons: breeze [Plasma], breeze [GTK2/3] Terminal: konsole CPU: Intel i7-8809G (8) @ 4.200GHz GPU: AMD ATI Radeon RX Vega M GH GPU: Intel HD Graphics 630 Memory: 8898MiB / 32031MiB

I do - every time I unlock my screen, Plasma crashes, and my windows get randomly distributed around my virtual desktops.

Oddly enough, if I only have one monitor enabled, it doesn't happen. And yes, I've nuked my preferences several times.

I have the same problem consistently on PopOS which uses GNOME just across two monitors. As a bonus, in the redistribution process, windows are randomly resized to a lot larger sizes. I suspect this is related to me leveraging the experimental scaling features in GNOME which is hard to avoid using 27inch 4K monitors. Really wish the window management would be more polished but I have no skill in that domain to make it better.

I'm running three screens and don't have the same problem. I did a clean format before installing KDE, though, just because that computer had been upgraded from one version to another for around ten years.

Are you using Wayland? If so, try X11.

Multi-monitor works well for me but I have one annoying issue which is that one line of pixels bleeds over the edge of one monitor into the next.

Nor do I.

I would even venture to say that, as I discovered last month with several Debian setups, it is the best multi-monitor plug'n'play experience I have had so far.