If you're going to use a VPN, please read about its policies and try to understand them. I was horrified to learn about this VPN service from Facebook that is now being promoted in its iOS app (I don't use the app, but anything to do with Facebook generally worries me). The Onavo VPN service from Facebook is disguised as a protection mechanism but tracks the user for the benefit of Facebook.

Quoting from this recent news: [1]

"But Facebook didn’t buy Onavo for its security protections.

Instead, Onavo’s VPN allow Facebook to monitor user activity across apps, giving Facebook a big advantage in terms of spotting new trends across the larger mobile ecosystem. For example, Facebook gets an early heads up about apps that are becoming breakout hits; it can tell which are seeing slowing user growth; it sees which apps’ new features appear to be resonating with their users, and much more.

This data has already helped Facebook in a number of ways, most notably in its battle with Snapchat. At The WSJ reported last August, Facebook could tell that Instagram’s launch of Stories – a Snapchat-like feature – was working to slow Snapchat’s user growth, before the company itself even publicly disclosed this fact."

[1]: https://techcrunch.com/2018/02/12/facebook-starts-pushing-it...