Does IANA (https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xml#variable)) run the registry for IPv6 Multicast groups? “We do not make allocations directly to ISPs or end users except in specific circumstances, such as allocations of multicast addresses"
There are only 112 registered multicast addresses? That seems low.
Are some IPv6 multicast packets globally routable? Wikipedia says both yes and no.
Should we be allowing packets with multicast addresses in/out of our network?
Globally unique multicast destination addresses have become unnecessary since the advent of SSM. If you look at the IPv4 registry, you’ll what was essentially a land-grab of Group D address space back when global multicast delivery was considered “on the horizon”, and ASM was the only option. Then there was GLOP for automatic assignments based on ASN, then SSM. I co-authored a draft back in ~2003 (from memory…) to deprecate global IPv6 ASM, but was over powered by vendor vote-stuffing, and it was shot down. Nearly two decades later, a similar draft emerged and is now a BCP: RFC8815
No more global IPv6 group address assignments required.