Partitioning boot disk on Big Sur?

Because I'm just an absolute daredevil, I have Big Sur running as a fresh install from b1 in a brand new APFS container with no other OS's or partitions on-disk.

I've tried to partition in BootCamp, Disk Utility, and Disk Utility via Recovery. No dice.

Is this blocked by System Integrity?
I have the same problem, except that I am trying to remove the Big Sur partition. It doesn't work. I hit "apply" and then "partition" and then nothing happens. Did you resolve the problem by any chance?
Partitioning boot disk on Big Sur?
 
 
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