Blackmagic Ultra Monitor 3G in 2021 PP
I was recently told by your tech support that 2021 PP does not support playback through the Blackmagic Ultra Studio Monitor 3G dongle on the Mac Mini M1. However, it does work on 2020 PP with no issues. I think something got broke in 2021 PP because it doesn't even show up in the PP preference menu, even though it is installed on the computer.
Blackmagic is updating their PPro plug-ins, to be ARM native.
In the meantime, you should be able to get the current plug-ins to work, if you run PPro in Rosetta2 (compatibility) mode.