I don't know if this should be considered as bug or "just changed behavior" but it is annoying.
sshd -T works in FreeBSD 11.4 (OpenSSH_7.5) and prints details about current configuration but it does not work with the same configuration file in FreeBSD 12.2 (OpenSSH_7.9).
# sshd -T
'Match Group' in configuration but 'user' not in connection test specification.
Once I have any "Match" in sshd_config then sshd -T does not work. It needs additional -C user=fakeuser to print configuration. (I just needed to view supported ciphers)
You can try it with default sshd_config and add something like this:
Match group sftponly
...or just ucomment the section "Match User anoncvs".
I think sshd -T should still work without -C as it was in older versions and print configuration for any non-matched criteria.