Steps to reproduce:
- create a Qt application with a single window
- add a QOpenGLWidget to the window (showing any static content)
- add a QWidget of the same size to the window so it ends up in front of the OpenGL widget
- set the background of this widget to rgba(0, 0, 0, 128)
- add a QProgressBar or any animated widget as child to this widget
Up to Qt 6.2.1 the widget creates a semi-transparent overlay and runs the animations fine.
Since Qt 6.2.1 the widget itself as well as it's animated children will create black drawing artefacts (see the attached video)
The Issue is observed on macOS 11., 12. as well as on Windows 10.