I'm very confident that RADOS is not supported.
RADOS is the underlaying object engine that block, object and file is built on top.
RADOS stands for reliable autonomic distributed object store

What I think we are trying to say here, is that we Support RHCS - RGW, which stands for Red Hat Ceph Storage - Rados GateWay

also, how come a specific, unsupported version is listed ? There is no version specificed for any of the other solutions...

RHCS-3 (v12.2.x) went EOL on June 27. 2023, according to: https://access.redhat.com/support/policy/updates/ceph-storage

Reported by: rh-ee-hemoller

https://access.redhat.com/documentation/en-us/openshift_container_platform/4.12/html/backup_and_restore/application-backup-and-restore#annotations:09a72341-6a1f-416c-8e61-2f26b25e7f4e