Pool generated on 1.9 series does not mount datasets successfully on 2.x series

[JMoVS]

System information

Type	Version/Name
Distribution Name	mac OS
Distribution Version	10.15.7 vs 11
Linux Kernel
Architecture	Intel vs ARM
ZFS Version	1.9.4 vs 2.1 rc3
SPL Version

Describe the problem you're observing

Describe how to reproduce the problem

I have an external zpool, which contains an encrypted dataset and which is not yet "upgraded". When I connect it to my ARM M1 MacBook Air on Big Sur, it reports data errors and I cannot mount the datasets. A scrub finds lots and lots of errors.
When I connect the same pool to my Catalina Intel mac on 1.9 series of OpenZFSonOSX, and I scrub, the errors go away and I can mount all datasets no problem.

I'm a bit lost on how to provide good diagnostic data - let me know how I can help.

Include any warning/errors/backtraces from the system logs