Created attachment 159645 [details]
KRunner application window invisible, but outline is visible.

SUMMARY
KDE pop-up windows, such as KRunner or volume controls, are not displaying their content properly but only show an outline. The window shadows appear correctly.

There might be more pop-over like applications involved, it just so happens that I directly notice the mentioned applications behavior.

STEPS TO REPRODUCE
1. Open KRunner by pressing Alt + F2 or using the assigned shortcut or attempt to change the volume using the volume controls or the volume hotkeys.

OBSERVED RESULT
When KRunner or the volume controls are opened, the pop-up windows appear with an outline but do not display their content. The window shadows are visible and when putting an application name into KRunner, it opens it, suggesting that the applications are working correctly. But no actual information or controls are visible in the pop-up windows.

EXPECTED RESULT
When opening KRunner or the volume controls, the pop-up windows should display their content properly. This includes showing search results and the current volume level. The windows should appear fully functional and provide the expected information and controls for the respective applications.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.3.7-zen1-1-zen (64-bit)
(available in About System)
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.107.0
Qt Version: 5.15.9
Graphics Platform: X11

ADDITIONAL INFORMATION
- Screenshots attached