I have a Time Machine backup volume, and I have a new Mac, but this volume won't mount on the new Mac. Workarounds?

Old Mac was iMac 27 late 2015, Monterey. New Mac is Mini M2 Pro, Ventura. Time Machine drive is a Thunderbolt 2 RAID. I can connect it with an adapter, but it doesn't mount. It still works fine connected to another older iMac, and I can mount it over the network, but Time Machine won't recognize it as a usable backup.

I thought of using the other Mac to restore from it to a second external drive, but of course the Time Machine app on the other Mac doesn't see it as a restorable backup, since it isn't a backup of the local system.

I can browse files, but that isn't useful, since it is a 3 TB volume — I just want to restore to the most current state, which would fit on a 500GB volume.