Backup question- Downgrading from Big Sur to Catalina
About a week ago, I upgraded from Catalina to Big Sur, restoring my data from a time machine backup. Now, I need to go back to Catalina. Normally, I'd just blow out the OS and restore from my time machine, but I'm being told that I'm going to have a problem because of the ~1 week of Big Sur data on the TM drive. Questions:
Is my current TM backup actually useless for this type of downgrade? And, more importantly....
Is there another backup/restore option or process available to me that would be roughly equivalent to TM? I'm perfectly willing to buy something if it will make this process easier.
Any input is appreciated.