I am using bind9 on Proxmox 9.0 / Debian Trixie base. I had what looks like the same problem.
What I found was that in /etc/apparmor.d/usr.sbin.named it was missing the abi , declaration at the beginning of the file. AppArmor silently failed to apply the rules. In my install script added this and boom, rules process. if ! grep -qE 'abi <abi/(3|4)\.0>' /etc/apparmor.d/usr.sbin.named; then sed -i "1i abi <abi/4.0>,\n" /etc/apparmor.d/usr.sbin.named fi I also had to add the local rules: /run/systemd/notify w, /proc/version_signature r, Now it starts and works flawlessly.
