Without patch and sysctl net.inet.ipsec.debug=1 we have such messages for IPv6 packets:
ipsec_common_input: no key association found for SA 0T\^S\^Z\^A����_/00005fb7/50
ipsec_common_input: no key association found for SA 0T\^S\^Z\^A����_/00005fb7/50
ipsec_common_input: no key association found for SA 0T\^S\^Z\^A����_/00005fb7/50
and with patch:
ipsec_common_input: no key association found for SA fe80::11/00005fb7/50
ipsec_common_input: no key association found for SA fe80::1:11/00003d59/50
ipsec_common_input: no key association found for SA fc00::11/00003d57/50
ipsec_common_input: no key association found for SA 10.9.8.11/00003d55/50
ipsec_common_input: no key association found for SA 10.9.8.11/00003d55/50