It’s been a while since I’ve dealt with any of this….but as I remember it, the installation of macOS 12.3 on the M1’s internal boot drive did not interfere with the MOTU UltraLite’s operation. But when I booted from a cloned external SSD, running 12.3, the UltraLite would not run. Reinstalling the MOTU driver on the booted external did not solve the problem. Please keep in mind this issue presented itself on a bootable backup, not the internal SSD. And on an M1 Max.
The warning prompts that the OSX boots were throwing out due to the legacy MOTU drivers are silicon M1-based, as far as I know. Not sure if older Intel chipped MBPs would do the same with higher OS installations.
I’ve been seeing the warning prompts after every incremental OSX update all the way up to 13.4.1, simply because I never bothered to purge the boot drive of the older MOTU driver installation. The newer drivers for the MOTU M2 are unaffected.