Note: The file path I've highlighted in red doesn't exist in Catalina, but if you follow the closest thing to it that does exist you see what Mike's talking about, although in reverse.
This is the closest I can get to that path in Big Sur.
Originally Posted by artie505
Mike's response to my question may be "quoted" as "Installing Big Sur on top of a CCC data clone and running Migration Assistant on top of a Big Sur installation yield the same results."
Agreed. But that does not mean you can clone or re-clone a data volume onto an existing Big Sur drive and end up with a bootable system.
In Catalina a virtual run time volume is created at boot time using elements from the system volume and the data volume. In Big Sur that virtual volume is created, and signedat Install time and is stored on the boot drive as an APFS snapshot. That snapshot is the bootable volume.
If we knew what it was we were doing, it wouldn't be called research, would it?
