Data can be both, in which case GDPR right still apply. Several GDPR fines have been handed down for processing business data about a person. Especially (but not only) data about sole proprietors/solo traders.
Got a link? Because while I don't doubt the logic, it just seems too esoteric to be an actual "issue" that people know about. Plus, I can't find anything.
„ personal data’ means any information relating to an identified or identifiable natural person (‘data subject’)“.
This is a business, not a natural person.