Bug 483819

Created attachment 167364 [details]
Demonstration of the bug in LibreOffice. The lower screenshot shows the expected appearance, achieved with the XWayland workaround.

SUMMARY
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STEPS TO REPRODUCE
1. Go to System Settings > Display & Monitor > set Scale to 125%
2. Open LibreOffice and check out the size of the toolbar and other elements
3. Open any image in Gwenview > Show Editing Tools > Annotate and check the size of the toolbars on the left and on the bottom

OBSERVED RESULT
All elements of the windows are scaled up way above 125%. As a result, they take up a notable part of the screen. Some QT layouts end up bigger than their windows, making elements inaccessible.

EXPECTED RESULT
Apps should be scaled to the configured scale of 125%, and all elements should fit within their respective windows.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Arch Linux 6.8.1-arch1-1 (64-bit)
(available in About System)
KDE Plasma Version: 6.0.2
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2

ADDITIONAL INFORMATION
This problem has appeared after upgrading to Plasma 6.
The workaround I've found for this is to force QT to use XWayland on per-app basis, for example: "QT_QPA_PLATFORM=xcb libreoffice --calc"

Gwenview's Annotate behaves weirdly even though Spectacle's Annotate behaves normally (i.e. correct scaling is applied), but I wasn't able to get Spectacle to screenshot itself. Attached is a demonstration in LibreOffice.