It was in the update message in the system settings itself.
I’ve opted out of the 13 beta before without wiping when a similar message said I could, but I believe I opted out before even starting the download.
I know I could’ve waited, but I figured since I was given the chance I would take it and wait before google introduces any new bugs they won’t fix until release
Edit: lol in the article it says to just ignore the downgrade prompt, so I guess we’re all good
MargotRobbie