pflog flooded with igmp queries

The pflogs on my firewall and on a new system I'm installing (-current
with pretty much a default pf.conf) are flooded with igmp query
entries. Neither system has a log rule for such action.

Ex:
===================================
rule 1/(match) pass in on em1: 192.168.1.20 > 224.0.0.1: igmp query [ttl 1]
===================================

pf.conf:
===================================
# $OpenBSD: pf.conf,v 1.55 2017/12/03 20:40:04 sthen Exp $
#
# See pf.conf(5) and /etc/examples/pf.conf

set skip on lo

block return # block stateless traffic
pass # establish keep-state
===================================

Reason? Solution?

Thanks!