NFS4: CentOS 7 client with a Fedora 32 server

[Braden McDaniel]

I'd like to support a CentOS 7 client from a Fedora 32 NFS4 server.
 Other Fedora 32 clients can mount the volume just fine using:

$ mount -t nfs4 my-server:/my-export-root/foo /foo

But when I try this from a CentOS 7 client, I get:

mount.nfs4: Operation not permitted

Is there any bit of configuration I can do on the client and/or server
to make this work, short of allowing fallback to pre-4 NFS versions?