Docker artifacts being automatically deleted despite no policies/tasks enabled

Nexus OSS 3.66/docker repo
I’m facing the following problem: I don’t want to delete the artifacts, but they are being deleted automatically. leaving only up to 5 latest tags. That is the case with Nexus OSS 3.66 at mine with docker repo, which has no Cleanup polisy nor Delete unused images tasks bound to it. I first suspected the policy or task was the reason, but I unattached both from this subject repo and the deletions still occur. For instance, when there is an image deployed one day as a 6th image in docker repo folder, the oldest image is auto-deleted overnight resulting in only 5 latest available. We’re using standardized version tags (ie 1.0.1, 1.0.2…), not using “latest”, not overwriting existing tags.
Any hints at possible diagnostics are welcome.