Distribution Upgrade showing distribution not understood or mixed

When I set the language to English and go to “Distribution update”, I see:

I installed Trixie and then installed freedombox manually.

This happens when contents of /etc/apt/sources.list are not understand. Could you please post the contents of the file? Ensure you remove comments. Change “stable” to “trixie”. Move sources other than official Debian to a separate files inside /etc/apt/sources.list.d/

There is no /etc/apt/sources.list, there are two files in /etc/apt/sources.list.d:

$ ls -la
total 16
drwxr-xr-x 2 root root 4096 Aug 11 23:15 .
drwxr-xr-x 9 root root 4096 Aug 11 22:28 ..
-rw-r--r-- 1 root root  588 Aug 11 22:28 debian.sources
-rw-r--r-- 1 root root  233 Aug 11 23:15 freedombox2.list
$ cat debian.sources
# Modernized from /etc/apt/sources.list
Types: deb deb-src
URIs: http://deb.debian.org/debian/
Suites: trixie
Components: main
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

# Modernized from /etc/apt/sources.list
Types: deb deb-src
URIs: http://security.debian.org/debian-security/
Suites: trixie-security
Components: main
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

# Modernized from /etc/apt/sources.list
Types: deb deb-src
URIs: http://deb.debian.org/debian/
Suites: trixie-updates
Components: main
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

$ cat freedombox2.list
# This file is managed by FreedomBox, do not edit.
# Allow carefully selected updates to 'freedombox' from backports.

deb http://deb.debian.org/debian trixie-backports main
deb-src http://deb.debian.org/debian trixie-backports main

We don’t yet have code in place to read the new style *.sources file. You can safely ignore this condition. You only need to worry about it for the next update to Forky in two years later. We will update the code soon to read these new files. Meanwhile, if you really want to see a better message in the Distribution Update page, then you can convert the debian.sources file into old style /etc/apt/sources.list file.

Thanks. It was during an “apt upgrade” operation that I had the automatic suggestion to run “modernize_sources” which resulted in this new format. I guess I can leave it this way then.