It isn't only, it's later: https://gitlab.gnome.org/GNOME/d-feet/blob/master/src/dfeet/window.py

# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.

As mentioned in our packaging docs:

-only licenses, such as GPL-2.0-only, should only be declared as such when the upstream explicitly states “only”, otherwise it should always be -or-later.

This shouldn't be 80-col or have hard wraps.