Fwiw, this article says the name of the app is Clue. As a dude, I have no need of such an app, but as a security minded individual, will encourage my female friends to use it if needed and hope the developers continue to have security in mind.

Virginia Governor Glenn Youngkin has blocked a bill in the state that would have banned law enforcement from enforcing search warrants for menstrual data stored in tracking apps on mobile phones or other electronic devices,

And as a Virginian, I will once again vote against the enemy of security and privacy: Glenn Youngkin.