This is very strange, don't they pop up this error?

Are you testing there using compatibility mode? Maybe the issue is that in the discussion thread they were using windows 98 compatibility, which is so archaic it doesn't hit the above conditional?

Yes, I was thinking of writing a solution for it, and I found it while testing.
And my windows version (Looks like microsoft doesn't allow .net core programs to use lower compatibility configurations than vista) does not allow to choose windows 98/ME compatibility mode, the minimum is windows vista

So there is a big question, how did that person use the windows 98/ME compatibility setting, maybe it didn't work at all

but a little strange, according to Microsoft docs, Environment.OSVersion should return a real OSversion but not the OS select in compatibility settings

@cdwcgt It seems the osu!.exe in %AppData%\Local\osulazer\app-2022.xxxx.0 is a .net core program, but the wrapper in %AppData%\Local\osulazer is not.

This might seem like a hassle (for code test), and it looks like he does inherit the setting
But this will require the program to start as an administrator so he will receive this error

from Environment.OSVersion.Version

that it, look like everything from before vista will return the real OS

Considering that starting as an administrator is also in the compatibility settings, maybe it is a good choice to prompt the user to check the compatibility test in ElevatedPrivilegesChecker?