pull replication seems ummount replicated dataset

I am pulling recursively whole datasets from FreeBSD system.
perun task
Disabled Include DAtaset Properties (as i am cloning ROOT fs for backup purpose)
Disabled full filesystem Replication (i don't wish to Truenas mount over this on own FS)
i altered mount points of dataset to mount /mnt/pool0/perun.../
i can mount those datasets triggering zfs mount -a ...
it will stay mounted until new snapshots will show on source system.
Truenas will replicate and unmount those datasets.
previusly those stayed mounted. so i had RO access to them...