Facebook is the latest company to violate Apple's new app guidelines surrounding data collection. According to a report by The Wall Street Journal, Facebook pulled Onavo Protect, a VPN app, from Apple's App Store after the iPhone maker determined that Onavo violated its data-collection rules.

Facebook purchased the Israeli company Onavo back in 2013. Since then, its free-to-download app has been marketed as a VPN service that blocks harmful websites and keeps users' personal data safe.

However, Onavo also allows Facebook to track and analyze customer usage data. That treasure trove of data lets Facebook understand how customers use their mobile devices when they're not using the main Facebook app. The app's description in the Google Play Store (where it remains available to download) includes a statement about how Onavo works to Facebook's benefit.

"As part of providing these features, Onavo may collect your mobile data traffic," the description states. "This helps us improve and operate the Onavo service by analyzing your use of websites, apps and data. Because we're part of Facebook, we also use this info to improve Facebook products and services, gain insights into the products and services people value, and build better experiences."

Apple's new app guidelines prohibit such collection and use of customer data. Recently, Apple has taken steps to increase the security and privacy measures on its platforms, and it has started enforcing existing rules more stringently. Apple's App Store Review Guidelines state that developers and their apps cannot collect and share data with third parties for purposes that aren't related to improving the app's overall experience or advertising.

To enforce these rules, Apple removed apps that shared location data with third-parties. It also banned developers from creating and selling databases made from Contacts and address book information. Users already had to opt in to allow apps to access such information, but Apple's new rules further restrict what developers can do with that information once they have it.

Facebook pulled Onavo from the App Store after discussing the matter with Apple and after Apple suggested it take down the app voluntarily. iOS users who already downloaded Onavo can still use it, but it's not available in the App Store for new users to download.

Tech companies have been under a lot of scrutiny recently about how they handle customers' data. Apple and Facebook have publicly disagreed on their respective approaches to data privacy. After Facebook's Cambridge Analytica scandal, Apple CEO Tim Cook criticized Facebook's handling of customer data and made a point to differentiate Apple's business model (one that sells devices and services) from Facebook's (one that monetizes its customers). Facebook CEO Mark Zuckerberg fired back at Cook by saying his comments were "glib" and "not at all aligned with the truth."