MultipleDefaultStorageClasses alert fires even when there is only one default SC

In three clusters, I am receiving the alert:

"Multiple default storage classes are marked as default. The storage class is chosen for the PVC is depended on version of the cluster.

Starting with OpenShift 4.13, a persistent volume claim (PVC) requesting the default storage class gets the most recently created default storage class if multiple default storage classes exist."

But the alert clearly shows only one default SC:

"Red Hat recommends to set only one storage class as the default one.

Current default storage classes:

ocs-external-storagecluster-ceph-rbd"

This is confirmed with 'oc get sc'

NAME                                             PROVISIONER                             RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
ocs-external-storagecluster-ceph-rbd (default)   openshift-storage.rbd.csi.ceph.com      Delete          Immediate           true                   351d
ocs-external-storagecluster-ceph-rbd-windows     openshift-storage.rbd.csi.ceph.com      Delete          Immediate           true                   11d
ocs-external-storagecluster-cephfs               openshift-storage.cephfs.csi.ceph.com   Delete          Immediate           true                   351d
openshift-storage.noobaa.io                      openshift-storage.noobaa.io/obc         Delete          Immediate           false                  351d