This issue occurs when we enable replication for a VM to the same site. This issue has been observed widely when source VM has thin disk.
Replication Datastore going out of space may depend on actual data on the source disk, it may takes few days to weeks to fill the destination datastore.
Changing datastore or datastore type will not help, i.e, local datastore to iscsi or to fiber, will not change the result
Even though source base disk is 20 or 30 GB, hbr-disk gets full on the disk, found unmap command which try to full fill all the disks.