If the police can tie the IP to a person, then it "can be tied". Some courts decided before GDPR that IP addresses can't convincingly be enough to tie a person

If the police can tie the IP to a person, then it "can be tied". Some courts decided before GDPR that IP addresses can't convincingly be enough to tie a person to a crime committed with that IP address, but that is not to say it isn't PII, or can't be tied to a person.