First of all they use much more than the device IP to identify individual devices. IPv4 is no longer all that useful for identification with things like CGNAT being common.
But with IPv6 they’ll see my device IP, then they’ll see the same device with completely different IP, then again. Same for my kid’s device. But again, all of the above applies. It is a concern, but there are much better ways of tracking you anyways.
First of all they use much more than the device IP to identify individual devices. IPv4 is no longer all that useful for identification with things like CGNAT being common.
But with IPv6 they’ll see my device IP, then they’ll see the same device with completely different IP, then again. Same for my kid’s device. But again, all of the above applies. It is a concern, but there are much better ways of tracking you anyways.