You can be tracked with either, but IPv6 is not functionally worse than IPv4 in that regard. You could argue that IPv6 is less anonymous than CGNAT, but CGNATs

You can be tracked with either, but IPv6 is not functionally worse than IPv4 in that regard. You could argue that IPv6 is less anonymous than CGNAT, but CGNATs usually have to keep detailed logs, so that balances out. All the tricks for anonymizing IPv4 (VPN, NAT, Tor, etc.) are equally feasible on IPv6.