IP addresses can be uniquely identifying. I've had the same IP for years, it's static, and if you did a Google search for it a few years ago, you got straight to my full name and location (because that used to be on whois database for my domain names, which point at my IP; thankfully they no longer include that info in whois).

IPs are personal data.

see https://gdpr.eu/eu-gdpr-personal-data/ section "Identifiable individuals and identifiers"

IPv6 without privacy extensions is pretty close to uniquely identifying.