Second-granular timezone offset format not documented

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/13/functions-formatting.html
Description:

I would like to request additional documentation on the timezone format that
can be returned.
Context: I had a problem with the HDBC-postgresql library, it cannot parse
the second-granular timezone offsets returned by PostgreSQL.

Here is an example of a format that I don't think the documentation
currently covers:
janus=> set timezone to 'America/Mexico_City';
SET
janus=> select '1920-12-25' :: timestamptz;
timestamptz
------------------------------
1920-12-25 00:00:00-06:36:36
(1 row)

Note how the response has a very weird timezone offset. I guess it is valid,
but the documentation should note this as an edge case, since timezone
offsets are typically only in minutes.

Thank you for your patience.