I found your thread as I was trying to solve a different problem. I’m on Big Sur.
My ‘18 MBP died and had to have a new system board. The hard drive was wiped or replaced.
I can’t restore from TM - Disk Utility says I have a file error 8. I had recently backed it up 2 weeks before it died too. Luckily, my data is all cloud, but my settings, Hazel rules, etc all are currently lost.
From this thread, I’ll try Disk Warrior to fix - so far other utilities didn’t seem to work - after a long time, I come back and my MBP is rebooted.
Assuming I can get it working, Is there a way to migrate existing TM files from HFS+ to APFS?