I've restored a Time Machine backup from an Intel machine to an M1 machine, but attempting to go the other direction does not work. I've tried backing up and restoring from a

• USB SSD
• network drive and
• Migration Assistant session

Nothing seems to work. The computer searches for Time Machine backups for a bit, then tells me there are none to be found. Is there a magic flag on the disk image or something similar that will force MacOS to restore the backup?