Created attachment 140695 [details]
screenshot of signal window after changing some kwin setting

SUMMARY

Hi,

When using kwin-wayland and some xwayland app and changing some kwin setting ( for example, i tested changing the "keep windows thumbnails" ) !and! if the window is not on view ( for example on another virtual desktop ), the window will get broken like in the screenshot attached.

Notice that if the window is being displayed/not minimized/not in another virtual desktop other than the current one, this bug will not happen.

Example in the screenshot: xwayland signal app.



STEPS TO REPRODUCE
1. Open a xwayland app, in this case of the screenshot, its Signal
2. Change into another virtual desktop other than the one where the window is
3. Change some kwin option/setting

OBSERVED RESULT
Window gets broken, with just the border shown and no contents

EXPECTED RESULT
Window to continue as it was before

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION