apt: wrong sources at /usr/share/doc/apt/examples/sources.list
It is useful to run restore /etc/apt/sources.list if you break it by running: sudo cp /usr/share/doc/apt/examples/sources.list /etc/apt/sources.list
However, in Trisquel 11, /usr/share/doc/apt/examples/sources.list is incorrectly listing the version codename "hirsute" (Ubuntu 21.04 (Hirsute Hippo)):
# See sources.list(5) manpage for more information
# Remember that CD-ROMs, DVDs and such are managed through the apt-cdrom tool.
deb http://es.archive.trisquel.org/trisquel hirsute main
deb-src http://es.archive.trisquel.org/trisquel hirsute main
deb http://es.archive.trisquel.org/trisquel hirsute-security main
deb-src http://es.archive.trisquel.org/trisquel hirsute-security main
deb http://es.archive.trisquel.org/trisquel hirsute-updates main
deb-src http://es.archive.trisquel.org/trisquel hirsute-updates main
Suggestion
Copy /etc/apt/sources.list (this one is using "es" sub-domain so I think it's wrong: https://gitlab.trisquel.org/trisquel/package-helpers/-/blob/aramo/helpers/DATA/apt/trisquel/sources.list.in) to /usr/share/doc/apt/examples/sources.list /etc/apt/sources.list