[ceph-users] What does 'removed_snaps_queue' [d5~3] means?

Hello guys, We are facing/seeing an unexpected mark in one of our pools. Do you guys know what does "removed_snaps_queue" it mean? We see some notation such as "d5~3" after this tag. What does it mean? We tried to look into the docs, but could not find anything meaningful. We are running Ceph Octopus on top of Ubuntu 18.04.