I'm a bit confused, I tried to use a FSLogix profile currently used on a WS2016 on our new WS2022 and against all odds it seems to work. I'm pretty sure I read somewhere that it couldn't work...

They both use the v6 style profile so it works. Some people have seen issues with the conversion to the new start menu style on desktops. Don't plan on going backwards with it though. I have see it throw major errors after it is converted.

Thanks for your clarification.

It’s the same as doing an in place upgrade of the OS where the user profiles would all be local - going forward will work, going backwards might work, but don’t be surprised if a profile breaks