The upstream help text next to that kernel option says:
"""
Choose Y here to disable the use of NFS over UDP. NFS over UDP
on modern networks (1Gb+) can lead to data corruption caused by
fragmentation during high loads.
"""
I'll leave it to the kernel team to comment further.
This was first disabled on groovy, the first ubuntu release after focal:
root@g1:~# grep NFS /boot/config- 5.8.0-59- generic |grep UDP NFS_DISABLE_ UDP_SUPPORT= y
CONFIG_
The upstream help text next to that kernel option says:
"""
Choose Y here to disable the use of NFS over UDP. NFS over UDP
on modern networks (1Gb+) can lead to data corruption caused by
fragmentation during high loads.
"""
I'll leave it to the kernel team to comment further.