"Downgrading" could have been the problem - you may need to do a fresh install as it's possible remnants from Ventura are causing the issue.
Rekordbox launch crash after reinstailling Mac OS Monterey 12.6
I was on Mac OS Ventura Beta. Rekordbox didn't want to read my USB drive for export, so I downgraded back to Mac OS Monterey. After the installing the backup Rekordbox won't even start, and crashes right on launch. I downloaded Rekordbox126.96.36.199. to see if that helped, but same results. How can I fix this? I have a show this weekend. Happy to provide the error code if that helps.
That's what I did. I wiped the hard drive and started with a fresh install of Monterey. No "remnants" from Ventura. How can you help me fix this?
Try installing 6.6.1 and see if that launches.