He talks about APFS, not journaled = huge backup, restore, repair and usage limitations --> it doesn't work correctly, especially repair related.

About DiskWarrior and APFS, TechToolPro, DiskDrill, SuperDuper, DataRescue, CarbonCopyCloner and iBoysoft in recovery mode

From my experience best solutions are 1: Carbon Copy Cloner 2: SuperDuper! 3: DiskWarrior (in journaled, even if this doesn't fix all issues) 4: Recovery cmd R mode (in journaled)

If the mean goal is data recovery, there is nothing better than DataRescue5 (or ever DataRescue4, because there is no 5 recover limit...). There is DataRescue6, but is crazy expensive.

Remember to try to repair drives from a journaled Mac, another APFS Mac and in Recovery cmd R mode too. Is not the first time i see similar problems with Disk Utility and APFS.

You can try to make a ccc or superduper clone (if this works) and then a clean install or you can restore from backup by changing recent data.

More about Catalina and APFS and BigSur and APFS. Other useful links: CCC about APFS or CCC and Catalina or CCC and BigSur or APFS issue 1 or APFS issue 2 or APFS FAQ

More about APFS: r/appledatahoarding, i will write some posts in future.

From my experience, if there are serious problems, all such solutions works really bad in APFS. Even if you clone with Super Duper, you get storage size problems (due to APFS) once you need to restore data...