Block DHCP traffic on interface and not on vlans


I was wondering if I can block DHCP traffic when I have vyos boxes connected to each other and both have their own DHCP server.

If I don’t enable the eth0 interface traffic still gets through from both DHCP servers over the vlan interfaces which are enabled for DHCP-relay so I think I need to create some firewall rule ?

Or is there a more easy way ?