"If you carry a phone with you, you don’t have location privacy. Police are able to use devices called cell-site simulators, also known as Stingrays or IMSI-catchers, to monitor and collect data from all phones at a protest. Additionally, telecom and tech companies collect their own vast location databases from phones, and this sort of data is not possible to anonymize."
https://theintercept.com/2020/06/15/protest-tech-safety-burner-phone/
https://theintercept.com/2020/06/15/protest-tech-safety-burner-phone/