(I'm not sure if you are the right recipient, please reassign)

I'm working on a script to determine the latest version for stable for
a package automatically (more details on request). For the "plain"
stable version, the following can be used:
https://packages.debian.org/bullseye/amd64/manpages-de/download

(I use a package with a backport as example).

Now the backport can be retrived accordingly:
https://packages.debian.org/bullseye-backports/amd64/manpages-de/download

Whats missing are security updates. Using (as an example) Firefox-esr
I see on
https://tracker.debian.org/pkg/firefox-esr

a link called "stable security" to
https://packages.debian.org/source/stable-security/firefox-esr

However, this link says "Error".

and in yellow "two or more packages specified (firefox-esr
stable-security)"

So either the link, p.d.o or both are currently broken.

(Changing source → amd64 in the last link does not help either)