There is misunderstanding here, perhaps about what the OP asked. I’ve interpreted the question to be why there are two different ipv6 addresses. I suspect you’ve interpreted it to be why is there a ipv4 and ipv6 addresses. At least I hope so.

I gather that insulting internet randos is what you do for a living.

Cgnat is for ipv4, has nothing to do with ipv6. Suggest reading up on ipv6.

This is fairly normal to receive 2 ipv6 addresses, depending on your provider. In my case, I receive a /128 address (single global address), and a /48 address (delegated global prefix). In addition, there is the link local address that will be fe80:… Delegated prefixes allow your internal devices to be assigned a global address within that subnet and access ipv6 resources directly. Feel free to ask more.

I haven’t been able to move on from musicolete. The lyrics display and playlist handling is alluring. If you find something open source though, I’m all ears.