I am encountering an updating bug which seems to be introduced with PySide6 (I'm using 6.2.2.1, everything is working fine under PySide2 5.15.2).

Maybe related: I'm using KDE on debian bullseye (this results in a X11 environment, verified this with loginctl).

Using the attached minimal example, the QMdiArea is not properly updated and I also have the impression there are some visible artifacts on the window title bars. Here is a screenshot after resizing and moving the created MDI SubWindow around (note the vertical and horizontal stripes).

The issue is visible on this virtual environment

$ ./venv6221/bin/pip freeze
PySide6==6.2.2.1
shiboken6==6.2.2.1

but not on this one:

$ ./venv515/bin/pip freeze
PySide2==5.15.2
shiboken2==5.15.2