QGraphicsProxyWidget: rendered Arabic text incomplete in large font sizes when OpenGL is used

Arabic text seems to be poorly rendered and missing clear chunks of it for proxy widgets in a case where:

• QGraphicsView is given an OpenGL viewport
• font size is large enough
• high dpi scaling is enabled
• desktop display scale is 2

Steps to reproduce the problem:

1. run the attached example
2. toggle display scale factor between 100% and 200%
3. notice the difference in the left view

Disabling high dpi scaling, not using QOpenGLWidget as a viewport or using display scale of 1 makes the problem disappear.