Current guidance, although not definitive, is that IPs and similar identifiers are personal data iff the processor/controller can identify a natural person by combining them with other data it can legally access.
There's also legal precedent that IPs can be sufficient enough to identify a person.
and its absurd, rejected, and overturned. if i use your laptop, am i you?
Not to conclusively for all time identify a person, but that's not what we're talking about. It's still PII: personally identifiable information. Things that can be used to identify a person.
A first and last name is also insufficient to identify a person, are you going to argue that names aren't personal?
Maybe not to a "reasonable doubt" threshold, but it's a pretty strong identifier.