Drop-down menu is displayed at a wrong position in a wrong size

Issue:
A drop down menu can be displayed at a wrong position in a wrong size under follwing condisions :

• Use Qt 5.15.15 , Qt 5.15.16, Qt 5.15.17, Qt 6.6.2 or Qt 6.6.3
• An application has a main window and a sub window
• Prepare two monitors with diffrent DPIs and scaling settings, for instance : 
      Main monitor :  resolution = 2560x1600, scaling = 200%
      Secondary monitor : resolution = 1920x1080, scaling = 100%
•  Use "Extend these diplays" setting in display setting, and place the main window on the right, and the secondary monitor on the left, side-by-side.
• Set DPI awareness to "System" by setting in qt.conf as follows :
      [Platforms]
      WindowsArguments = dpiawareness=1

Steps to reproduce the issue:

• Run the attached reproducer with "#define SUBWINDOW_ON_2ND_DISP (1)"
• On the main window (titled "DPI-popup"), click "Test" on the menu bar, then a drop-down menu will be displayed in a smaller size.
• Move the main window a bit by dragging, then click "Test" again,  then a drop-down meny will be displayed at a wrong position.

Side note:

• The issue is not reproducible with Qt 6.7.1.  This issue can be reproduced with Qt 6.7.1 under an additional condition. (A comment will be added for details)
• This issue looks similar to QTBUG-102982, but I created this ticket because it is reproducible on a different OS (windows 11) and Qt versions.