Another error that should be causing replication to fail, but the system still says finished successfully:

[2021/08/10 10:00:29] WARNING [replication_task__task_7] [zettarepl.replication.run] For task 'task_7' at attempt 1 recoverable replication error
RecoverableReplicationError('cannot receive incremental stream: destination vol_1/ contains partially-complete state from "zfs receive -s".
warning: cannot send \'vol_1/ @ auto_20210810_0000_Daily_ \': signal received')

While it says it's a recoverable error, no action seems to have been taken to recover this. This replication job appears to be permanently stuck and unable to proceed. That certainly doesn't seem like a successful outcome.