When backing up VM or CDI DV its possible to get a PartiallyFailled backup
In the logs youll be able to see something like that:

In backup describe --details:
  Velero:    name: /prime-cb3e67a7-3365-491e-9fa5-c3df99192865 message: /Error backing up item error: /error executing custom action (groupResource=volumesnapshots.snapshot.storage.k8s.io, namespace=kvp-e2e-tests-swlqn, name=velero-prime-cb3e67a7-3365-491e-9fa5-c3df99192865-sf8r7): rpc error: code = Unknown desc = failed to get volumesnapshot kvp-e2e-tests-swlqn/velero-prime-cb3e67a7-3365-491e-9fa5-c3df99192865-sf8r7: client rate limiter Wait returned an error: rate: Wait(n=1) would exceed context deadline
             name: /test-vm message: /Error backing up item error: /error executing custom action (groupResource=virtualmachines.kubevirt.io, namespace=kvp-e2e-tests-swlqn, name=test-vm): rpc error: code = Unknown desc = VM would not be restored correctly

In backup log:
"Waiting for CSI driver to reconcile volumesnapshot kvp-e2e-tests-swlqn/velero-prime-cb3e67a7-3365-491e-9fa5-c3df99192865-sf8r7. Retrying in 5s" backup=openshift-adp/test-backup-1731249330041542604 cmd=/velero logSource="/remote-source/velero/app/pkg/util/csi/volume_snapshot.go:713" pluginName=velero"

4.16.3, 4.17.1

Sometimes

1.Create a VM with storage class that supports snapshots
2.Create velero backup

Backup PartiallyFailed

Success

This is a racefull bug. It happens since in the time of the backup PVC' is being in terminating state, which prevent velero from creating a snapshot for it. 
We want to PVC' to be excluded from the backup