Erase content and settings: stuck in recovery mode and can only reinstall with a beta version

Macbook Pro 2020 A2338 (M1), I'm going to sell it, and my issue is 2-fold

1. After trying to Erase Content and Settings, it then restarts, then I connect to wifi and successfully activated it... then tried to restart but it remains in recovery mode (as far as I can tell). I followed this guide to do this: Erase all content and settings on Mac – Apple Support (AU)
2. In the recovery menu, for whatever reason "Reinstall macOS 12 Beta" is one the options. I did have macOS 12 Beta installed but I updated to 12.1 just before erasing content and settings, and also disabled my access to beta software both on the Software Update page and in the Apple Developer portal. Obviously I don't want to sell this to someone with a Beta version installed, but unsure how to change this.

I do have a feeling that if I was able to resolve the first issue, the second issue might not be a problem, but not 100% sure and would appreciate any assistance. All I want to do is have the device in a state where it's ready to be resold.

Thanks