Backup retention ignored (not using PBS)

[poisonborz]

Hey, I configured a backup job on the Datacenter node, and set "keep-last=1", but it is ignored, backups keep piling up.

Each affected node's logs just states

2024-03-18 21:05:07 INFO: prune older backups with retention: keep-last=1
2024-03-18 21:05:07 INFO: pruned 0 backup(s)

What could be done to debug this?