We received many errors on Kubernetes note about NFS protocol not supported occurred during checking mounted volumes from disk. What are those errors? Are these just warnings?

$ journalctl -f

E1015 04:00:09.802197 3414 kubelet_volumes.go:66] pod "e24b5a42-1ce0-4e4c-8e9f-1f7d6a00dac7" found, but error stat /var/lib/kubelet/pods/e24b5a42-1ce0-4e4c-8e9f-1f7d6a00dac7/volumes/kubernetes.io~nfs/ml-pv-prod-1: protocol not supported occurred during checking mounted volumes from disk