Just got off support for this same issue. I just updated to MacOS 12.0.1 Monterey today and the fix was to allow access to the AEServer application in the System Preferences.
System Preferences
Security & Privacy
Privacy Tab
Accessibility
Find "AEServer" in the list on the right and check the box to allow that app to control your computer.
This is the fix that worked for me. No more stray Windows events when using Cmd+Tab to switch applications on my Mac.