Historically, I have been a Mac user but I run GIS software in a Windows 10 VM quite a lot under Parallels 15. If I just tap the Command key, that opens the Windows Start Menu (is that what it's called?) however the shortcuts you mention - Win-S and Win-I don't work for me either. I am just using the default Parallels key mapping.
Not an issue for me, since I've never used those shortcuts. But, FWIW, your issue doesn't seem to be specific to Parallels 17, Windows 11 or the M1. I am using a 2018 Intel Mini with an extended Apple Magic Keyboard (space grey). Perhaps this has something to do with the type of keyboard?