I believe that the webcam output from the ATEM Mini fits within USB 2.0 data rates (480 Mbps maximum) as the original ATEM Mini only included a USB 2.0 port (with a USB Type C connector). Note there are settings for Input format, Color Space, and Video Range that may be useful to users. Select Device = Blackmagic Design, Resolution = 1920x1080, No to Use Preset, Frame Rate = Simple 59.94. The end user will not see a reversed image. This is not the Mini cropping but rather Facetime. Note the image in Facetime may be cropped or reversed. You should see Blackmagic Design in the selection. The Video menu allows the selection of camera sources and microphone sources separately. Check the signal in an app like Facetime. Put the cable back and do the Command-R and observe the device is back. To verify the device is actually connecting, pull the USB cable and do the Command-R to refresh the display. Other Blackmagic products use other names. In the Audio, Camera, and USB Device Sections, there will be a 'Blackmagic Design' entry. In the Apple icon upper left, select 'About This Mac -> System Report' The USB data cable would have a USB-C connector on the ATEM end and whatever USB, type A or C on the computer end. Not a thunderbolt cable and not a USB charging cable.

Blackmagic design atem mini