I think it's probably just the fact that the IPv4 stack has just received a lot more hardening because it's deployed everywhere (by necessity)... and IPv4 has h

I think it's probably just the fact that the IPv4 stack has just received a lot more hardening because it's deployed everywhere (by necessity)... and IPv4 has had a 15+ years lead over IPv6 on that whole hardening thing because it came later and a time where IPv4 was already pretty well established.