NFSv4.0 is the nominal support on FreeNAS
NFSv4.1 nominally included pNFS (parallel NFS = scale-out) which FreeNAS does not support
NFSv4.1 clients should be backward compatible with NFSv4 storage.. but not via pNFS
So.... FreeNAS supports NFSv4.1 clients, but not pNFS
TrueNAS SCALE has a plan to support NFSv4.1 with pNFS (scale-out).
There have been VMware issues with ESXI NFS v4.1 client
I don't know whether they have ben resolved. https://www.ixsystems.com/community/threads/nfs-4-1-datastore-mounted-as-read-only.69173/
I'm far from an NFS expert, but I'd be very surprised if the design goal for anything would be "break standard NFS 4.0 clients". It doesn't make sense.
This was fixed some time ago, you can now make nfs 4.1 mounts with multiple ip addresses and VMware will round robin them to get all the bandwidth of the individual links. The trick is to use VMware to carve up the networking.
My point is that you can't do this with Freenas because it doesn't support nfs 4.1, to use freenas, nfs and esxi, you have to use nfs 3