Teen suicides are up by a good bit. FB/Instagram popped up right around the time the trend started going up, perhaps a coincidence, but perhaps not.
https://www.pbs.org/newshour/nation/suicide-among-teens-and-...
https://www.pbs.org/newshour/nation/suicide-among-teens-and-...
And let's get real, this is not just a FB problem. If you really care about this, you have to burn a whole lot more than just FB. And it's probably going to include most internet companies. Cyberbullying is going to happen wherever teens spend most of their time on the internet.
We have important societal issues to solve. c54's comment touched on that in an insightful way. There are other things to balance here. Marginalized groups have benefited a lot from social media much like geeks benefited a lot from video games, D&D, and board games. But we don't like to talk about that because in many minds FB == the devil, and mentioning any benefit means propping up the devil. Soon we'll be talking about TikTok in the same manner.
This should be investigated but it needs to be done with an objective point-of-view. You do not have an objective point-of-view. Facebook does not have an objective point-of-view. The media definitely does not have an objective point-of-view. Let's at least try to be scientific.