I don't know if this is related but I've seen isps that put you behind a cgnat over ipv4 if you have ipv6 connectivity but they give you an ipv4 ip address just

I don't know if this is related but I've seen isps that put you behind a cgnat over ipv4 if you have ipv6 connectivity but they give you an ipv4 ip address just for you if you disable ipv6.