Last Tuesday, Apple announced a new software update that aims to improve iPhone users’ privacy.

Indeed, the announcement was made during a product event and should be available from next week. The update, called iOS 14.5, includes a new feature requiring applications to get explicit permission from users to track their activity and locations.

Prior to the new feature, called App Tracking Transparency, apps were free to track iPhone users without having to ask for permission. Now, even applications already on the phone will have to get explicit permission from users.

However, this new update might have a serious impact on digital advertisers such as Facebook, which rely heavily on following people through their iPhone so they can collect personal data and sell targeted ads. The privacy software could then cost digital advertisers billions of dollars.