Researchers from the University of Bologna, Italy and University College London, UK carried out a field study using an app specifically developed for this research. TrackAdvisor tracked more than 200,000 locations, identifying approximately 2,500 places and collecting almost 5,000 pieces of personal information concerning both demographics and personality. The most sensitive pieces of information were the ones about health, socio-economic situation, ethnicity, and religion. The study also shows how collecting such information can represent a violation of the users’ privacy.
Source: https://www.helpnetsecurity.com/2021/02/25/privacy-implications-location-tracking/