Database corrupted - can't downgrade

Hi - I'm running macOS Catalina and can't upgrade. However, I was able to install DVR 18 without complaint. It has a minimum system requirement of macOS Big Sur (which apparently isn't checked for by the installer). It ran to the point of upgrading my database and I was able to look at a few projects and fix up some where the media source files had been moved.
Now DVR 18 won't even start. The error dump says "missing symbol", which prompted me to reinstall and look at the system requirements. Fair enough, I should have checked that before.
I reinstalled DVR 17 which does work on Catalina (and Mojave, interestingly enough). It won't start as the database is now incompatible ("Incompatible (not upgradeable) database <18.1.0.003>, application requires <17.0.0.001>."
How can I downgrade the database? I do have a Time Machine backup but don't know where to look for it.
Any ideas?

[Rohit Gupta]

Which version of macOS 10.15 are you running?

I do have a Time Machine backup but don't know where to look for it.

If you first started with Resolve 16 or later then the default database location (assuming thats what you were using) would have been in your user library directory, so check there in your Time Machine backup
~/Library/Application Support/Blackmagic Design/DaVinci Resolve/Resolve Disk Database