I'm not sure if this is related to macOS 11.2 RC specifically, but the other night when I went to re-install macOS, I had a bout of bad luck.
Backed up all my data and user settings beforehand, thankfully. Boot into Recovery Menu to reinstall, the reinstall went fine initially, did not brick my firmware or anything, so at least that is fixed so far.
I got all the way through the reinstallation process, got up to the point where I had to set up my WiFi password and user account, the Setup Assistant. When I went to create my username and password, it was taking longer than usual, and eventually was greeted with a failed message for the username and password. Seemingly it created the User Account, but not the password, as when I shut down and started back up, I was at the macOS login screen, but couldn't login.
So figuring that I had a bad install or something, I reinstalled a couple more times to see if it would fix things, but nope.
There's no other way (as far as I'm aware) to re-launch the setup wizard, unless someone knows a way, and since Single-User Mode is now gone in Big Sur, it's next-to-impossible.
After that, I followed a series of instructions, which ultimately got me to Erase My Mac from the Recovery Menu, once I did that, absolutely everything was wiped off--At which point I was stuck at the Recovery Menu, unable to continue, had no other choice but to enter DFU Mode and use my 2016 MacBook Pro to Revive-Restore.
So long story short; APPLE, DO MORE BETA TESTING!