Comment 13 for bug 1954595

Same no luck:

$ LANG=C sudo apt install brz-debian/focal-proposed
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Release 'focal-proposed' for 'brz-debian' was not found

Could it be because I am using the closest apt mirror, which is in my case:

http://fr.archive.ubuntu.com/ubuntu

And that is has not yet been replicated up to that mirror?

My test is on Focal.