The format all images recently published by Red Hat was OCI. 
Previous images's format was Docker V2-2.
It was suddently changed 1 or 2 month ago.

This is very critical.

In OpenShift manual[1], Red Hat says "You can use any container registry that supports Docker v2-2".

[1] https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html/disconnected_environments/connected-to-disconnected

But due to this format change, container registries which support Docker v2-2 but don't support OCI are no longer usable for OpenShift.

any    

You can check the format using skopeo

eventrouter image:

  $ skopeo inspect --raw docker://registry.redhat.io/openshift-logging/eventrouter-rhel9:v0.4.0-384 | jq -rM .mediaType
  application/vnd.oci.image.index.v1+json

  $ skopeo inspect --raw docker://registry.redhat.io/openshift-logging/eventrouter-rhel9:v0.4.0-382 | jq -rM .mediaType
  application/vnd.docker.distribution.manifest.list.v2+json

cluster-logging-operator image:

  $ skopeo inspect --raw docker://registry.redhat.io/openshift-logging/cluster-logging-rhel9-operator:v6.2.3 | jq -rM .mediaType
  application/vnd.docker.distribution.manifest.list.v2+json

  $ skopeo inspect --raw docker://registry.redhat.io/openshift-logging/cluster-logging-rhel9-operator:v6.2.4 | jq -rM .mediaType
  application/vnd.oci.image.index.v1+json

fence-agents-remediation-operator image:

  $ skopeo inspect docker://registry.redhat.io/workload-availability/fence-agents-remediation-rhel9-operator:v0.5.1 --raw | jq -rM .mediaType
  application/vnd.oci.image.manifest.v1+json
  
  $ skopeo inspect docker://registry.redhat.io/workload-availability/fence-agents-remediation-rhel9-operator:v0.5.0 --raw | jq -rM .mediaType
  application/vnd.docker.distribution.manifest.list.v2+json

The mediaType is "application/vnd.oci.image.index.v1+json"

The mediaType is "application/vnd.docker.distribution.manifest.list.v2+json"

Why did Red Hat do such a big change without announcement?
The format should be reverted, then Red Hat should announce in the release note at least one version before making such a change.