What does "uniqueid disk ID=<guid>" do exactly to an OS drive?

I was under the impression that this simply changes the disk ID and that's it. However during my tests and messing around in a vm, I was unable to reverse this if used on the OS drive.

I would change the guid to something else, reboot into a blue screen (obviously cause BCD can't find correct guid), then use recovery to change the guid back. However, even if I change the guid back, the vm wouldn't boot and would still throw a blue screen. Is there something else going on that breaks the BCD and the boot other than the disk ID change?

Yep, I understand that much

What I'm saying is, I changed the ID from lets say xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx to yyyyyyyy-yyyy-yyyy-yyyy-yyyyyyyyyyyy. On restart, what you wrote happens, sequence interrupted, and you get a bsod on boot. Then going into recovery and using that cmd, I change the Y ID back to the X ID like it was originally and reboot. It still gives a bsod on boot.