Provide a Privacy and Cookie Policy
REQUIREMENT
Under most countries' laws it's mandatory that you disclose details related to privacy and your data processing activities. Mobile apps are no exception: they're required to provide a privacy and (if they make use of cookies) cookie policy. In order to be compliant, your policy must be up-to-date, understandable, unambiguous, and easily accessible throughout the app.
Failure to do so can result in massive fines, app store rejection, leave you open to litigation and negatively affect the credibility of your app.