Hello,
the Vms are since Promxox 4 .4 or so in so-called ZFS volumes short ZVOLs . ZFS volumes are datasets that represent a block unit.
In short, your VM disks are no longer in the shap of a file on the file system, but are a block device, so to speak.
Path to the zvols :
root@fal-pve02 ~ #...