Just use "madison", here's an example with openssh-server:
apt-cache madison openssh-server
openssh-server | 1:8.4p1-5+deb11u7 | http://deb.debian.org/debian-security bullseye-security/main amd64 Packages
openssh-server | 1:8.4p1-5+deb11u3 | http://deb.debian.org/debian bullseye/main amd64 Packages
If you want to downgrade or set a specific packag........