I happened to stumble over the fact that bullseye Sources files contain numerous versions of some of the packages.
For example: $ wget http://ftp.debian.org/debian/dists/bullseye/main/source/Sources.gz $ zgrep -A 2 'Package: util-linux' Sources.gz | grep -v Binary Package: util-linux Version: 2.33.1-0.1 -- Package: util-linux Version: 2.34-0.1 -- Package: util-linux Version: 2.36-3 Those three versions happen to be the current versions from stable, testing, and unstable. Does anyone know why these are all in this one file? The version from unstable is the most surprising.