I have applied the patch to Stable 13.1 and tested on several systems that previously demonstrated https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=272018
The VPD is correctly and consistently displayed via pciconf -lV <pci addr> with this patch.

Move setting of UCOM_FLAG_LL_READY back to original location.

@rmacklem: yes my FreeBSD13 is a little stale. I did some crude IO bench marking; the graphs are very spiky, but it appears that I got around 200-250 MB/sec with the 128k and 250-300++ MB/sec with 1m. Multiple writers all from the same client over a 1G link.

I've pulled this into my FreeBSD Stable13; I've verified that a client (ubuntu 18x) negotiates wsize/rsize = 131072 by default and that by adding vfs.nfsd.srvmaxio=1048576 to /etc/sysctl.conf, the same client negotiates wsize/rsize = 1048576. I have also done some cursory IO testing.