I cloned a package in the FiFo-Gui with the only change being "compression: lz4" and changed the package for an lx-zone to this new package. It seems that the change is not reflected on the hypervisor.
The same result after rebooting the zone. In the json-specification of the zone, there is no "zfs_root_compression" field.
Here are the chunter logs during the pacakge change.