I use Anki on a system with Ubuntu (now version 21.10) with the Mate desktop environment (version 1.26.0). It worked until yesterday, when I installed the system update. Since then, Anki starts but the windows are broken and it is impossible to use. Other programs that use Qt seem to be unaffected, and Anki works normally on GNOME.
Update: the problem seems to have solved by itself.
Update2: The problem is manifesting again. I have discovered that it is related to the new NVIDIA drivers. Anki works if I switch the system to Intel or “NVIDIA on demand”. It makes no difference whether I enable OpenGL or not. On GNOME, Anki works also with the NVIDIA drivers.