It's an issue with Tk where the font name used in the output doesn't match that used by Postscript. I added a fix for this for DejaVu Sans Mono some years ago, but the quick change to Menlo missed this. I will add a check for Menlo with the find-replace code.

On Jan 8, 2021, at 11:34 AM, pd-list-request@lists.iem.at wrote:

Date: Fri, 08 Jan 2021 07:17:00 +0100
From: IOhannes m zmölnig <zmoelnig@iem.at>
To: pd-list@lists.iem.at
Subject: Re: [PD] Menlo in MacOS X
Message-ID: <F247B545-1CA1-4183-AEFB-A556AACB8C77@iem.at>
Content-Type: text/plain; charset=utf-8

Am 8. Jänner 2021 02:41:10 MEZ schrieb "Julián Villegas" <villegas.julian@gmail.com>:

For example, would this be worth of opening an issue in
GitHub? 

no.
i dont think its a "bug" in Pd.

Pd tries to use "Menlo" on macOS, because it fixes a couple of issues.
if that font cannot be found, the font engine of your system will automatically use a similar font, eg "Courier".
the same happens with ghostscript.