Goverments (depending on juristiction) have laws requiering isp's to keep track of cgnat port combos. So not only is there no privacy from ipv4 cgnat. Now the isp must also spend a lot of money on the nat state tracking database.
If you need that kind of privacy, use a vpn and the tor onion network.
Yes it does take extra work. Problem is often that that work was done in the past when isp implemented their ipv4 metodology. And instead of using the ipv6 rollout as a chance to improve their design and operations. They just add ipv6 into their ipv4 design and methodology. They encumber their ipv6 rollout with their decades of technical debt and cruft they have normalized in their ipv4 world. And it will makes things harder for themselfs when trying to turn off ipv4 in the core.
Maybe we can get good IPv6 support now ( lemmy.world ) Englisch
https://www.sidn.nl/en/news-and-blogs/cgnat-frustrates-all-ip-address-based-technologies