This 29 January 2019 video says about itself:
Facebook paying $20/month to install VPN to collect and gain access data from your phone.
“The VPN is reportedly similar to Facebook’s Onavo Protect app that was pulled from the Apple App Store last year for privacy violations.
However, Facebook calls on iOS users to side-load the Facebook Research app by declaring the social network to be a trusted developer.”
Furthermore, a representative for security app Guardian Mobile Firewall told the outlet Facebook could also collect private messages in social media apps, messages and media from chat apps, and your location.
From Techcrunch in the USA today:
Facebook pays teens to install VPN that spies on them
Desperate for data on its competitors, Facebook has been secretly paying people to install a “Facebook Research” VPN that lets the company suck in all of a user’s phone and web activity