deb http://deb.debian.org/debian bullseye main contrib non-free
deb http://deb.debian.org/debian bullseye-updates main contrib non-free
deb http://deb.debian.org/debian bullseye-backports main contrib non-free
deb http://security.debian.org/debian-security/ bullseye-security main contrib non-free

Debian 12 (Bookworm ) -- Full sources.list
deb http://deb.debian.org/debian bookworm main contrib non-free non-free-firmware
deb http://deb.debian.org/debian bookworm-updates main contrib non-free non-free-firmware
deb http://deb.debian.org/debian-security bookworm-security main contrib non-free non-free-firmware

Debian 13 (Trixie) - /etc/apt/sources.list.d/debian.sources

Types: deb
URIs: https://deb.debian.org/debian
Suites: trixie trixie-updates
Components: main contrib non-free non-free-firmware
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

Types: deb
URIs: https://security.debian.org/debian-security
Suites: trixie-security
Components: main contrib non-free non-free-firmware
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

Bullseye is archived now (but not debian-security)

deb http://archive.debian.org/debian bullseye main contrib non-free
deb-src http://archive.debian.org/debian bullseye main contrib non-free

deb http://security.debian.org/debian-security bullseye-security main contrib non-free
deb-src http://security.debian.org/debian-security bullseye-security main contrib non-free

deb http://archive.debian.org/debian bullseye-updates main contrib non-free
deb-src http://archive.debian.org/debian bullseye-updates main contrib non-free

deb http://archive.debian.org/debian bullseye-backports main contrib non-free
deb-src http://archive.debian.org/debian bullseye-backports main contrib non-free