IPv6 can be a privacy issue, sure, but it's no less secure, my firewall is still blocking all incoming IPv6 traffic.
The issues with IPv6, in my experience come from its relative complexity, compared to IPv4, and also from forgetting to manage it at all, as it often uses different tools, firewalls, e.g. ip6tables vs iptables, or the fact that Ubiquiti EdgeRouters don't expose ANY IPv6 firewall configuration in the GUI at all.
The issues with IPv6, in my experience come from its relative complexity, compared to IPv4, and also from forgetting to manage it at all, as it often uses different tools, firewalls, e.g. ip6tables vs iptables, or the fact that Ubiquiti EdgeRouters don't expose ANY IPv6 firewall configuration in the GUI at all.