21H2 is a really old Windows build, the issue may be that it is a LTSC install and certain drivers may not be 100% compatible.
On the support side of things Framework may just tell you that LTSC are not officially supported as their devices have been tested with standard builds of Windows 10 and 11.
I suspect that if Windows 11 was installed on a second partition or external drive for this machine everything would be coming up fine driver wise. Therefore it is something that is different with the LTSC build and then it is just an OS issue.