I don’t have any sources files in my /etc directory. My Debian install in general is really weird, since the default apt sources came only with some CD ROM source, which did not work with the Internet. So I had to manually add all sources myself (probably caused some of my troubles…) These are my sources right now
deb http://security.debian.org/debian-security bookworm-security 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/ bookworm-backports main contrib non-free non-free-firmware deb http://deb.debian.org/debian/ bookworm main contrib non-free non-free-firmware
I’m assuming these are correct, as they all got that bookworm in them.