The question above for the most part, been reading up on it. Also want to it for learning purposes.
Your ISP is doing it wrong, which I guess you already know. I get a /64 net via DHCPv6 for my LAN which is pretty standard.
+1 to dual stack. Too much of the internet is v4 only, missing AAAA, or various other issues. I’ve also had weird issues where a Google/Nest speaker device would fail 50% of the time and other streaming devices act slow/funky. Now I know that means the V6 net is busted and usually I have to manually release/renew. Happens once every few months, but not in a predictable interval.
Security is different, but not worse IMO. It’s just a firewall and router instead of a NAT being added in. A misconfigured firewall or enabling UPnP is still a bad idea with potentially worse consequences.
Privacy OTOH is worse. It used to be that each device included a hardware MAC as part of a statelessly generated address. They fixed that on most devices. Still, each device in your house may end up with a long lived (at least as long as your WAN lease time) unique IP that is exposed to whatever sites you visit. So instead of a unique IP per household with IPv4 and NAT, it’s per network device. Tracking sites can differentiate multiple devices in the house across sites.
This has me thinking I need to investigate more on how often my device IPv6 (or WAN lease subnet) addresses change.
I get a fat /48 network, just in case I need one septillion, two hundred and eight sextillion, nine hundred and twenty-five quintillion, eight hundred and nineteen quadrillion, six hundred and fourteen trillion, six hundred and twenty-nine billion, one hundred and seventy-four million, seven hundred and six thousand and one hundred and seventy-six individual IPs.
IPV6 is pretty wild, we could effectively give every service connecting to every client, in every direction, for every single individual bit its own dedicated address without getting anywhere near using that address space.
Just wait until IoT takes off and every key on your keyboard has a unique address