On désactive les services:
sudo systemctl disable avahi-daemon.socket
sudo systemctl disable avahi-daemon.service

On stoppe les services:
sudo systemctl stop avahi-daemon.socket
sudo systemctl stop avahi-daemon.service

On interdit à cups de lancer le service:
sudo vim /lib/systemd/system/cups-browsed.service

En commentant la ligne:
Wants=avahi-daemon.service

Ou en sed:
sudo sed -i "s/Wants=avahi-daemon.service.*/#Wants=avahi-daemon.service/g" /lib/systemd/system/cups-browsed.service