$ python
>>> import psycopg3
>>> print([info for info in psycopg3.pq.Conninfo.get_defaults() if info.keyword == b"channel_binding"])
[ConninfoOption(keyword=b'channel_binding',
envvar=b'PGCHANNELBINDING', compiled=None, val=None,
label=b'Channel-Binding', dispchar=b'', dispsize=8)]
compiled is expected to be "prefer" or "disable" as per docs.
Please find a patch attached.
Cheers
-- Daniele