bad exports list line message happening suddenly on 15-stable after buildworld/kernel upgrade

Hi,

I'm seeing these lines appear in /var/log/messages on the nfs server:

===
May 21 17:17:30 desktop mountd[34297]: can't change attributes for /external20tb/04: netcred already exists for given addr/mask
May 21 17:17:30 desktop mountd[34297]: can't change attributes for /external20tb/00: netcred already exists for given addr/mask
May 21 17:17:30 desktop mountd[34297]: bad exports list line '/external20tb/00        -maproot'
May 21 17:17:30 desktop mountd[34297]: can't change attributes for /external20tb/02: netcred already exists for given addr/mask
May 21 17:17:30 desktop mountd[34297]: bad exports list line '/external20tb/02        -maproot'
May 21 17:17:30 desktop mountd[34297]: can't change attributes for /external20tb/04: netcred already exists for given addr/mask
May 21 17:17:30 desktop mountd[34297]: bad exports list line '/external20tb/04        -maproot'
===

The exports actually work, in that they can be used by clients laptop1 and rpi4b

They are zfs sharenfs dirs.

/etc/exports looks like this :

===
/external20tb/00        -maproot=root -alldirs laptop1 rpi4b
/external20tb/02        -maproot=root -alldirs laptop1 rpi4b
/external20tb/04        -maproot=root -alldirs laptop1 rpi4b
===

/etc/zfs/exports is identical

What's going on? This only started happening after upgrading from:
FreeBSD 15.0-STABLE stable/15-n282003-d2fb6b8f80cc

to:
FreeBSD 15.1-STABLE #0 stable/15-n283597-3ae682909950
--