Actually I would argue anything that relies on debug data to patch private internal functions or literally scanning for specific instructions in memory would be considered by Microsoft to be a bit of a hack. I believe many of the windhawk things do that though I don't know if that particular one does or not.
That all sounds tricky for the average user to understand for sure. If the mod titled, "Vertical Taskbar for Windows 11" is in fact considered a hack by Microsoft, even I couldn't tell it was.
That said I suspect I know why it isn't happy with S11, in particular it would be unhappy with enhanced taskbar enabled as that wouldn't know what was going on. With that disabled on the other hand I would have expected to have been happier as it handles vertical taskbars on Win10.
Yes, enhanced taskbar does have to be turned off. But even with that turned off any app pressed opens the start 11 menu rather then the intended app. The only solution is to assign the windows key to open start 11 rather then the mouse click. Not sure why that happens