Comment # 1 on bug 1141883 from Wolfgang Bauer

Judging from the backtrace, this upstream commit might help here:
https://cgit.kde.org/qtcurve.git/commit/?id=b7da5ec7e2965332e3922dfb03a3d100aa203b94

Please try the packages from here (once it is published):
https://download.opensuse.org/repositories/home:/wolfi323:/boo1141883/openSUSE_Tumbleweed

(I think qtcurve-qt5 should be enough, but better update the other packages as
well if you have them installed)