[Regression] Resizing a Window with an QOpenGLWidget child causes the whole window to flicker

Note: This issue is observed on macOS - I do not have access to other platforms to test.

This issue is also not reproducible with Qt 6.3.2

Problem:
Manually resizing a Window that contains a QOpenGLWidget child anywhere in it's child-hierarchy causes major flickering and redraw stutter over the whole window.

Steps to Reproduce:

• build and run the "hellogl2" example on a mac using Qt 6.4.0 or Qt 6.4.1

Expected Behaviour:
The window and all it's children should resize smoothly and without any flicker

Actual Behaviour:
Major flickering on all widgets, even those outside of the QOpenGLWidget.
See the attached video for a demonstration.