This alert fires when more than one default virtualization storage class exists.
A default virtualization storage class has precedence over a default Kubernetes storage class for creating a VirtualMachine disk image.
If more than one default virtualization storage class exists, a data volume that requests a default storage class (storage class not explicitly specified), receives the most recently created one.
Obtain a list of default virtualization storage classes by running the following command:
$ kubectl get sc -o jsonpath='{.items[?(.metadata.annotations.storageclass\.kubevirt\.io\/is-default-virt-class=="true")].metadata.name}'
Ensure that only one storage class has the default virtualization storage class annotation.
If you cannot resolve the issue, see the following resources: