I currently use two monitors, so I have two separate desktops, with two different wallpapers. Whenever I boot up, they either switch the wallpapers between them or the 2nd monitor has a black wallpaper. Also, the “screen modifier” panel is always much longer than needed:
This happened after a fresh install of Manjaro 20.1, on KDE. Also, don’t know if it matters or something, but I’m on testing branch and I use Materia KDE theme.
Could you post the output of inxi -Gazy? Incidentally my system has the same behaviour, i have yet to track down the source of it though. My current guess would be for it to be some race condition. Do Widgets/desktop files also switch locations when the desktops switch?
The behaviour is absolute random for me though, sometimes happens every second boot, sometimes doesn’t happen for a week or 2. It seems to be random for OP as well. I’m currently testing a xinerama config, and so far it seems to work, but I can only be sure with time.
Searched on Qt Jira bug reports and didn’t find anything, but I’m glad to see it is reported and perhaps on a way to be fixed. Maybe the extension of the switch display panel is a Qt issue or a KDE issue as well.