Weird bridge monitoring event when vlan aware bridge configured

Question

I Configured a VLAN aware bridge on my system with the command:

ip link add <bridge_name> type bridge vlan_protocol 802.1Q vlan_filtering 1
ip link set dev <bridge_name> up

Later, When adding another bridge link (ip link add name yoav type bridge) and using "bridge monitor" we can see the log event:

7a:26:53:bb:86:e5 vlan 1 master * permanent (mac address of the bridge link).

What is the meaning of this event? why there is no interface?

the same can be seen while reading netlink messages of type RTM_NEWNEIGH - ndm_ifindex is 0.

Thanks!