To add on this,many will allocate a much smaller prefix. If you are being tracked by IP, the whois of your v6 address will contain what prefix is delegated,but

To add on this,many will allocate a much smaller prefix. If you are being tracked by IP, the whois of your v6 address will contain what prefix is delegated,but even if they don't use whois they can simply track "subnets" (prefixes) as a data point, if a cookie or browser fingerprint is seen on multiple addresses, the address part will help pin point a specific user. With v4 you have NAT and CGNAT now that obscures your public address a bit, you lose that with v6. For privacy, you need your address to be shared by many other users. This is one reason VPNs are useful, your public IP is shared by many. It's the same problem with browser fingerprinting, the more you try to prevent it, the more trackable data points you create (e.g.: one more extension or one less default setting that makes you a few steps more unique than everyone else).