In sys/kern/vfs_cache.c struct namecache nc_hash field changed from a doubly linked list to a singly linked list in commit 2b86f9d6d013a9ad8b1f8d03286018e785d5b3f6, breaking reading filenames in lsof. (Yes, it was almost impossible to debug)
Patch submitted upstream at https://github.com/lsof-org/lsof/pull/180 but until its merged we may want to apply it to our port.
(In reply to Damjan Jovanovic from comment #0)
Noted with thanks:
Use user mode APIs on FreeBSD by DamjanJovanovic · Pull Request #184 · lsof-org/lsof