This is a known issue in 2023 and 2024 that use the Qt libraries. So, it is really a Qt bug.
This will require an update to the Qt libraries which involves much testing. The Trimble SketchUp team is aware and working on it.
See this topic thread with many responses that was started last April:
It seems that the Qt libraries may have problems with 1440 vertical resolution displays ?
The takeaway is that (besides using a machine with a discrete Nvidia GPU) is to run SketchUp on the display that is set to the Windows Main display. Also, be sure that your display scaling is set to recommended scale and resolution is set to recommended resolution, for all displays. (No guarantees as even these settings have issues on some machines.)
I myself have not had the “orphan menu” problem but did have other issues when I was running SketchUp on a display that was not set to be main. My issues went away when I set my external UHD display to be the main Windows display.