I'm stumped by this problem with a friends iMac (Big Sur on a Retina 5K, 27", Late 2014 with a 2TB fusion drive and the R9 M290X 2GB GPU). He has constant, random freezing, buffering and crashes so I assumed the fusion drive was on it's way out so I backed up the drive using Superduper (latest...
If you ever use a T2 Mac with the Startup Security Utility in the Recover Partition to control external booting and other boot parameters, this is for you.
If you clone the original installation to another volume, boot off that, and erase the original, the token to use this utility is gone. You...