iocage missing allow.mount.fdescfs jail parameter, it is impossible to enable it in iocage. maybe missing some others.
please note that iocage has been mostly abandoned upstream https://github.com/iocage/iocage/issues/1289#issuecomment-1268638684
(In reply to Mina Galić from comment #1) Yes, i know. Bit it is very easy to patch this, simply add fields in a few places in the code found by grep. I can do this myself, but I'm not familiar with the procedure.