There is one silver bullet to fixing this issue:
- System > Multitasking
- Uncheck "Show my snapped windows when I hover over taskbar apps ..."
The label of this setting makes absolutely no sense to me, but it will keep windows from grouping for any reason. I snap windows to the corner of my display all of the time, but this setting is not referring to single window snapping, instead groupings of windows. As a result Alt+Tab will not show groups and mouseover the taskbar item will not show the group, should one have been accidentally created.
I might add that if two windows are side-by-side after having snapped one to the left corner and one to the right corner and you place your cursor to the top or bottom edge (depending on corner of the display each window appears) a large splitter will appear allowing you to resize both. This does not mean the windows are grouped. This is just a feature of Windows Explorer for non-grouped windows that happen to be side-by-side after having been snapped.
BTW, credit to this site for helping figure this out: https://www.elevenforum.com/t/enable-or-disable-show-snap-groups-on-alt-tab-task-view-and-taskbar-in-windows-11.3498/