I had some bad driver issues that led to me need to 'reset' Windows from the local recovery partition. This recovered my machine and got it bootable again. Afterwards, WSL2 wasn't installed, so I tried to install it. It rebooted, etc, then fetched Ubuntu 22.04 from the Microsoft Store as usual. However, instead of keeping my previous WSL2 content it started a new user:
Ubuntu is already installed.
Launching Ubuntu...
Installing, this may take a few minutes...
Please create a default UNIX user account. The username does not need to match your Windows username.
For more information visit: https://aka.ms/wslusers