Storage facet cleanup removes images from repository without cleanup policy

Hi all,
I have a question for Nexus OSS 3.25.1-04. I have a docker hosted repository which has no cleanup policy. I have identified several times that images are disappearing. According to logs from webhooks, image are removed by initiator *TASK

{"timestamp":"2020-10-16T22:00:23.222+0000","nodeId":"AE39F241-9F92B94D-311554B8-D894AE47-9006E26E","initiator":"*TASK","repositoryName":"xxx.yyy","action":"DELETED","asset":{"id":"3a6deaad2473b51cd157e35f78db2f7d","assetId":"d3BoLm9zczozYTZkZWFhZDI0NzNiNTFjZDE1N2UzNWY3OGRiMmY3ZA","format":"docker","name":"v2/automation/ubuntu-oss-robot/manifests/sha256:17f808244e31fdb18db97eaff2af346ad81bee1da8864a1260bfd41464154de8"}} 

which is basically matched to this log event:

2020-10-16 22:00:00,006+0200 INFO [quartz-11-thread-19] *SYSTEM org.sonatype.nexus.quartz.internal.task.QuartzTaskInfo - Task 'Storage facet cleanup' [repository.storage-facet-cleanup] state change RUNNING -> WAITING (OK)

How is possible that Nexus removes any image by its own ? Do you have such experiences or any hint ? thanks