It's the same with https://issues.redhat.com/browse/OADP-6033

Create backup resources.

[cloud-user@ocp-psi-executor-xl qwang]$ oc get backup -A
No resources found

$ oc version
Client Version: 4.20.0-rc.1
Kustomize Version: v5.6.0
Server Version: 4.20.0-rc.1
Kubernetes Version: v1.33.3

$ oc get clusterversion
NAME      VERSION       AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.20.0-rc.1   True        False         26d     Cluster version is 4.20.0-rc.1

$ oc get csv -n openshift-cnv
NAME                                       DISPLAY                    VERSION   REPLACES                                   PHASE
kubevirt-hyperconverged-operator.v4.20.0   OpenShift Virtualization   4.20.0    kubevirt-hyperconverged-operator.v4.19.6   Succeeded

$ oc get csv -n openshift-adp
NAME                   DISPLAY         VERSION   REPLACES               PHASE
oadp-operator.v1.5.1   OADP Operator   1.5.1     oadp-operator.v1.5.0   Succeeded