Is it possible to rollback to an older version of PL6 on OSX?

See this topic for why I want to run an older version (anything older than the last couple weeks would be fine).

Current PL Version 6.18.0 build 74
OSX Sonoma 14.5

If you have a previous installer downloaded and saved, you can delete the current PL and install the older version.
Or if you have a Time Machine back you can roll back to a previous date and restore the PL of that time.

If a database structure update occurred between the current version of PL and the older version that will be reinstalled, I’m not sure that the current database will be compatible with the older version of PL. This should normally not happen for 2 versions having the same major version number.

Only DxO can say.

When PhotoLab pops up the “update available” window, I do the following:

I also download the installer and keep it safe.
DPL databases don’t usually change between dot releases.

Your case: Restore DPL from your time machine backup.