>personal data’ means any information relating to an identified or identifiable natural person (‘data subject’); an identifiable natural person is one who can be identified, directly or indirectly, in particular by reference to an identifier such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person;
The lack of an actor in the sentence is key. In other words, just because you can't identify the person with the data you have doesn't mean it's not PII. If a piece of data can theoretically be traced back to a person then it's PII.
GPDR is extraordinary in its attempts to be as broad as possible. As written it covers effectively every bit of data you collect.