Window scaling of 175% causes black line below title bar with QOpenGLWidget at certain window sizes

When a QOpenGLWidget is rendered and the screen scaling is set to 175%, a black horizontal line appears below the title bar.

• This worked correctly in Qt 5 (was tested with 5.12.12) and presumably doesn't work since Qt 6 (was tested with Qt 6.2.4).
• Tested under Windows 10 and Windows 11.

Steps to reproduce:

• Build and run the simple program hellogl2 from examples. See: https://code.qt.io/cgit/qt/qtbase.git/tree/examples/opengl/hellogl2?h=6.4
• Run hellogl2, it should look like this:
  

• Change windows scale (under Windows 11): Display settings→ Scale & Layout: Set scale to 175%:
  

• Look at the hellogl2 window again. If you don't see the black line so far, resize your window by dragging its corners.
• Then you should notice this: