You should've backed up before you installed the beta. You can however revert to any saved backup on One UI 3 or older.
But! You can backup your entire gallery to google photos for fairly cheap rates. That way you can revert and restore your photos that way and deal with settings manually.
the main things to back up are contacts, documents and photos... almost everything else can be replaced. fresh installs for apps are cleaner than installs from backups. that way you don't import any bad settings from a backup.
Hello @Batfone ,
It is not required to backup via smart switch , you are free to use any backup service to backup your data. When you do withdraw from beta and use smart switch to roll back to Android 11, your data on device is erased not from your cloud backup or any backup on PC.
One UI Beta Team