

Next time, when you make major changes like ZFS upgrade, create a checkpoint and keep it for a while. You can roll back everything, even the pool version.
I personally like to run ZFS on a bare metal server, just the plain OS, no further “NAS” or virtualization software.
I don’t really know what your use cases are, so I cannot tell if it’s adequate for you.

It’s also not uncommon in enterprises that things break needlessly.