Kubernetes mount.nfs: access denied by server while mounting

It's probably because the uid used in your pod/container has not enough rights on the NFS server.

You can runAsUser as mentioned by @Giorgio or try to edit uid-range annotations of your namespace and fix a value (ex : 666). Like this every pod in your namespace will run with uid 666.

Don't forget to chown 666 properly your NFS directory.

You have to set a securityContext as privileged: true. Take a look at this link