Mouse cursor incorrectly scaled after display switch on high DPI system

I'm using a machine running Linux (Pop!_OS 22.04) with X11 on a HiDPI display (4k, fractional scaling), and this machine is on a KVM.

When I start up any Qt 6 application, the mouse cursor appears at its normal and correctly scaled size.

If I use the KVM to switch to another machine, and then back, the mouse cursor suddenly becomes super-tiny.  I've attached screenshots showing this problem in Qt Creator, both before and after switching displays.  (I can reproduce this in my own Qt 6 apps as well.)

In the comments to QTBUG-98720, I recently learned that Ilya Fedin is quite familiar with the likely root cause of this issue, and has attempted to submit the following changes to fix it in the past:

https://codereview.qt-project.org/c/qt/qtbase/+/427313
https://codereview.qt-project.org/c/qt/qtbase/+/417817