Is this space included in the amount of space used?
Maybe the ingress is not registered in the database due to some errors like “database is locked”?
It’s also possible that you are experiencing compaction, which by default creates up to 10 files of 1 GB each simultaneously for each satellite until the compaction is complete.
You may also try to check the ingress usage on the debug port or via storagenode API.
Perhaps it’s better to enable a dedicated disk feature: