Completely replace the contents of /etc/apt/sources.list with the following:
deb
http://ftp.us.debian.org/debian bullseye main contrib non-free
deb
http://ftp.us.debian.org/debian bullseye-updates main contrib non-free
deb
http://security.debian.org bullseye-security main contrib non-free
deb
http://ftp.us.debian.org/debian bullseye-backports main contrib non-free
deb
http://download.proxmox.com/debian/pve bullseye pve-no-subscription
After you have corrected /etc/apt/sources.list, run the following command:
apt-get -q update && apt-get -y -q dist-upgrade && apt-get -q -y autoremove --purge && apt-get -y -q clean
Then reboot. After reboot, run the above command again. Then please provide a list of all packages. From the GUI, go to the node, Summary, and click Package Versions. You can copy and paste it here.