Increased system keyspace size after backups finish

We are running weekly backups of our FDB clusters, and in our largest cluster the system keyspace [\xFF, \xFF\xFF) seems to be growing week by week. It grows during the weekly backup, and when the backup is completed, it goes down again, but not to the level it was before the backup started.

When looking at the distribution of data in the system keyspace, we that most of the data is under the \xff\x02/backup-agent/uid->config/prefix, and most of the keys have the form \xff\x02/backup-agent/uid->config/[uid]snapshotRangeFileMap... where [uid] seems to be a 16-byte UID.

Is this expected, and is there any way to clean it up?