Code
~ $ cat /etc/apt/sources.list
deb http://deb.debian.org/debian bullseye main contrib non-free
deb http://deb.debian.org/debian-security/ bullseye/updates main contrib non-free
deb http://deb.debian.org/debian bullseye-updates main contrib non-free
# Uncomment deb-src lines below then 'apt-get update' to enable 'apt-get source'
# deb-src http://deb.debian.org/debian bullseye main contrib non-free
# deb-src http://deb.debian.org/debian-security/ bullseye/updates main contrib non-free
# deb-src http://deb.debian.org/debian bullseye-updates main contrib non-free
thank you, i changed the source list!
apparently just the http was wrong. Is there a reason why my source list contained just the http instead of https addresses?
now everything went smoothly!