If you're using a Wayland session, you might try switching to X11. Most of the KDE6 issues I've been seeing on reddit are due more to Wayland issues.

    Thanks @zmaint, now I know what is causing it.
    Now I have another problem: How do I make X11 the default? When I switch it in SDDM, it goes back to Wayland the next boot. Is there a way to set the default? I use KDE.

      Archdevil I believe it should stay as the last session type you logged in as. I know there has been strangeness with sddm after this update, possible it is an sddm bug.

      From terminal you can confirm what session you are running with echo $XDG_SESSION_TYPE It might be possible that SDDM is showing wayland but you are still actually running x11 or vice versa.

        Unfortunately it still defaults to Wayland... What can I do about that?

          Archdevil Might change your SDDM theme to the generic default Breeze. There are a lot of theming issues right now since the QT version also changed.

            SDDM should remember the last used session type, either Wayland or X11. I've seen no signs that this was broken in the upgrade.

            Regarding the theming issues I've made some tweaks to improve it. Namely I disabled the virtual keyboard by default since it seems to pop up by default on non-breeze themes (breeze can still use it by clicking the icon). I've also built a qt5 greeter which sddm will use if the theme metadata says that it only works with qt5. It will also try to load themes that don't declare a qt version as qt6 themes which MIGHT make them work. People using custom themes are still better off using themes that state that they are explicitly for Plasma 6 though as those should work reliably.

            SDDM doesn't do that unfortunately. I use the Breeze theme for SDDM, as provided by Solus. This is a pretty new installation without changing much. Installation was done less than a month ago.

            I hope someone can tell me what to do, as using wayland is not working...

              lf-araujo Yep. Works fairly well unless you game. Not a Solus issue. There's no native proton/wine support so everything has to be ran through another layer... xWayland. Creates a bunch of weirdness. Especially janky with launchers, extra windows, alt tabbing, context menus, etc.. I also ran into issues with context menus on flatpak chromium not drawing (ie black until you wiggled the mouse over them). It also apparently doesn't like Nvidia too much.

              I'd suppose if you were all AMD and weren't using any wine/proton related games/apps, it'd probably run just fine.

                  zmaint Actually I play games on Plasma Wayland since 5.27, but have an all AMD setup. I don't play too many different games, but don't have any problems so far.

                      kaktuspalme I tried it out for a couple days about 3 months ago. It was ok... but noticeably had issues. Quite a few of the games I play have launchers, it doesn't seem to like those extra windows. Chromium flatpak had serious issues with the context menus drawing. Could just be nvidia I reckon.

                      I absolutely noticed the performance difference between native wine/proton and xwayland.