The nfs rpc_lockd_flags and rpc_statd_flags was moved out of the ${name}_precmd() function and that broke things creating this regression.

I posted a patch to fix the 15.1-RELEASE nfs flags regression: bugs.freebsd.org/bugzilla/show_bug.cgi?id=296233#c2

There is also an easy workaround to implement until the problem is fixed in the next patch release.