seems to be related to specific type of apps? I realized this already for quite some time in yast2 software management. Works fine e.g. in libreoffice or apps like kmail, korganizer ect. System: Operating System: openSUSE Tumbleweed 20251216 KDE Plasma Version: 6.5.80 KDE Frameworks Version: 6.22.0 Qt Version: 6.10.1 Kernel Version: 6.18.1-1-default (64-bit) Graphics Platform: Wayland Processors: 16 × Intel® Core™ Ultra 7 255H Memory: 96 GiB of RAM (93.8 GiB usable) Graphics Processor: Intel® Graphics Manufacturer: TUXEDO Product Name: TUXEDO InfinityBook Pro Intel Gen10
KWin isn't responsible for how apps render their windows. Your issue is however caused by the option in Breeze only applying to QtWidgets apps.