Wireguard traffic treated as flowing into WAN port?

[abulafia]

Why does OPNsense treat traffic on my WireGuard interface as "in" traffic on WAN?

Code Select Expand

WAN Oct 19 18:08:48 10.10.100.1:5353 224.0.0.251:5353 udp Block private networks from WAN

Code Select Expand

__timestamp__ Oct 19 18:08:48
action [block]
anchorname
datalen 69
dir [in]
dst 224.0.0.251
dstport 5353
ecn
id 46266
interface igb0
interface_name WAN
ipflags none
ipversion 4
label Block private networks from WAN
length 89
offset 0
protoname udp
protonum 17
reason match
rid 1eb94a38e58994641aff378c21d5984f
rulenr 69
src 10.10.100.1
srcport 5353
subrulenr
tos 0x0
ttl 1

This is the mDNS repeater listening on my LAN, VLAN and WireGuard interfaces which all form part of my LocalNet interface group and are generally considered as local interfaces. My OPNsense wireguard interface/endpoint has IP 10.10.100.1.

I would have expected the mDNS repeater repeating DNS traffic emitting from the LAN/VLAN interfaces to the WireGuard interface and vice versa, however this shows as WireGuard mDNS traffic flowing "in WAN" which seems wrong.

Why does this trigger a "WAN in" rule? Seems like a bug to me ....?