[Widget] The view becomes black when docking back the window in Hellp GL2 example

Windows 10 

Qt Creator 14.0.1

Device: Raspberry Pi4 64 bit with Qt 6.8.0 RC

Steps to reproduce:

1. Open example - https://doc.qt.io/qt-6/qtopengl-hellogl2-example.html
2. Run the app on RPi device with '-platform wayland-egl / wayland' parameter
3. Undock the windows
4. Dock back the window

Expected: The 'Q' character is still visible.

Actual: The screen becomes black. Attached wayland_debug logs.

Reproducibility:  100%