@evilbunny2008

I ended up commenting out the 'deb' line in the opera-stable.list file and left it coexisting with the opera-stable.sources I created.

jepjepus@debian:/etc/apt/sources.list.d$ cat opera-stable.list
# This file makes sure that Opera Browser is kept up-to-date
# as part of regular system upgrades

#deb https://deb.opera.com/opera-stable/ stable non-free #Opera Browser (final releases)


jepjepus@debian:/etc/apt/sources.list.d$ cat opera-stable.sources 
Types: deb
URIs: https://deb.opera.com/opera-stable/
Suites: stable
Components: non-free 
Signed-By: /usr/share/keyrings/opera.gpg

Other browser's developers team already solved this issue.

Regards,
Josep

@Sherlockholmes007 this is still to be solved.
I get the same issue after upgrading to Debian 13 and modernizing sources for repositories.

So now you have 2 types of Debian: the modernized one (with .sources file) and the old style (with .list file).

I think that it is not so difficult checking a condition to act as it corresponds: adding or not the .list or the .sources file.

Thanks,
Joep.