It ultimately depends on what you’re doing (and can do) with those IPv6 addresses. If you can identify someone then it probably is. That’s for example if you h

It ultimately depends on what you’re doing (and can do) with those IPv6 addresses. If you can identify someone then it probably is. That’s for example if you have a web form with their details filled in— just make sure they know you’re keeping their IPv6 address for the avoidance of doubt. If you can give it to someone like their ISP, and they can identify someone for you, then it might be: especially if you have a relationship with that ISP where you do that. If not, then probably not.