Operation not permitted accessing snapshots in jailed dataset

Setup: jailed dataset is configured and given a mountpoint

root@host# iocage create -r 12.2-RELEASE -n gaol
root@host# iocage set jail_zfs=1 gaol
root@host# iocage console -f gaol
root@gaol# zfs set mountpoint=/data  tank/iocage/jails/gaol/data

Snapshots can be created and destroyed but contents cannot be accessed via .zfs path:

root@gaol# zfs snapshot tank/iocage/jails/gaol/data@testsnap
root@gaol# cd /mnt/data/.zfs/snapshot
root@gaol# ls
  testsnap
root@gaol# cd testsnap
ls: testsnap: Operation not permitted.