3. of Inference

Your geolocation data is as accurate as possible, even if you only really need to know which city the user is from.

Threat
	If you are collecting the most detailed geo-location data, you should have a good reason for doing so, you should have communicated that reason to the subject, you should only collect it when it is necessary to collect it, and you should likewise only retain it for as long as is strictly necessary. If recorded continually and stolen, that data could be used to determine the daily routine of a subject, from which someone could infer any number of things including their beliefs if they visit a place of worship, their political affiliations, their medical situation, and so on.
GDPR	Chapter 1, Art. 4 – 4. Chapter 2, Art. 5 – 1. (b) Chapter 2, Art. 9 – 1. ...