difference NFS proto and mountproto

in RHEL 8.8 when I am trying to test NFS tcp versus udp and versions 3 versus 4.0, 4.1 and 4.2, I observe on my nfs client a mountproto= in addition to proto= when typing mount. What is the significance of this and what does it mean? Should I be able to, in RHEL 8.8, have NFS operating showing specifically vers=3 and proto=udp on the nfs client? What does it mean, on the nfs client, when I see proto=tcp and mountproto=udp ?