Zack Whittaker, writing for TechCrunch:

According to Mozilla’s latest findings examining the privacy practices of period-tracking apps, Stardust was found to be sharing users’ sensitive health information with third-party analytics company RudderStack. This data included the user’s birthdate, birth control type, reproductive goals, and specific symptoms that the user was experiencing, and it tied that record to a unique identifier in place of the person’s name. (The FTC has long warned that this does not make the data anonymous or prevent it from being linked back to a person.)

“Your data is private. Period,” says period tracker Stardust. Not only is it not private, but users are even given a unique identifier. Stardust is simply a deplorable company.