Backup completes but vzborg reports it as failed

Hi.
I managed to complete a backup of a CT, but vzborg still reports the backups as failed:
root@proxmox:~# /usr/local/bin/vzborg backup -c remote --id '103' --purge
vzborg: Retrieving ssh://user@backup-host/mnt/backup/qdrop-proxmox repository info
------------------------------------------------------------------------------
Repository ID: xxx
Location: ssh://user@backup-host/mnt/backup/proxmox
Encrypted: Yes (repokey xxx)
Cache: /root/.cache/borg/xxx
Security dir: /root/.config/borg/security/xxx
------------------------------------------------------------------------------
                       Original size      Compressed size    Deduplicated size
All archives:              175.92 GB             76.20 GB            180.22 GB

                       Unique chunks         Total chunks
Chunk index:                42053039             90486150
------------------------------------------------------------------------------
vzborg: > Host qdrop-proxmox - Backup job started for guests 103.
vzborg: > Repository ssh://user@backup-host/mnt/backup/proxmox.
vzborg: > with purge option and retention "--keep-last=3 --keep-weekly=1 --keep-monthly=1".
vzborg: -> Beginning backup of CT 103 (dockerhost-unpriv)
INFO: starting new backup job: vzdump 103 --dumpdir /tmp --compress 0 --quiet 0 --mode snapshot
INFO: filesystem type on dumpdir is 'zfs' -using /var/tmp/vzdumptmp867422_103 for temporary files
INFO: Starting Backup of VM 103 (lxc)
INFO: Backup started at 2023-08-14 08:13:01
INFO: status = running
INFO: CT Name: qdrop-dockerhost-unpriv
INFO: including mount point rootfs ('/') in backup
INFO: excluding volume mount point mp0 ('/mnt/arrr-data') from backup (disabled)
INFO: excluding device mount point mp1 ('/var/lib/docker') from backup (not a volume)
INFO: excluding bind mount point mp2 ('/mnt/nas-homes') from backup (not a volume)
INFO: excluding bind mount point mp3 ('/mnt/nas-public') from backup (not a volume)
INFO: including mount point mp4 ('/mnt/backups') in backup
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: suspend vm to make snapshot
INFO: create storage snapshot 'vzdump'
INFO: resume vm
INFO: guest is online again after 2 seconds
INFO: sending archive to stdout
Connection closed by remote hostReading filessdump
INFO: cleanup temporary 'vzdump' snapshot
INFO: Finished Backup of VM 103 (00:36:31)
INFO: Backup finished at 2023-08-14 08:49:32
INFO: Backup job finished successfully
vzborg: --> Purging
Warning: "--prefix" has been deprecated. Use "--glob-archives 'yourprefix*'" (-a) instead.
Remote: Killed stale lock backupraspi.
Remote: Removed stale exclusive roster lock for host backupraspi pid 17086 thread 0.
Remote: Removed stale exclusive roster lock for host backupraspi pid 17086 thread 0.
Keeping checkpoint archive:              vzborg-103-2023_08_14-08_12_59.tar.checkpoint Mon, 2023-08-14 08:13:22 [xxx]
Pruning archive (1/2):                   vzborg-103-2023_08_14-04_47_56.tar.checkpoint Mon, 2023-08-14 04:48:20 [xxx]
Pruning archive (2/2):                   vzborg-103-2023_08_13-13_38_03.tar.checkpoint Sun, 2023-08-13 13:38:27 [xxx]
Connection closed by remote host
vzborg: <-- Done Purging
vzborg: <- Finished backup of CT 103 (dockerhost-unpriv).
vzborg: < Host proxmox - backup job complete!

VZBORG SUMMARY

TY   VMID  BCK.TIME  BACKUP  PUR.TIME   PURGE  NAME
CT    103  00:36:33  failed  00:27:43  failed  dockerhost-unpriv
How can I gather more logs to diagnose the issue?
g3492 / vzborg

Backup completes but vzborg reports it as failed #18
