This is a solid essay (and book review) on social media and teen mental health that includes much-needed academic research receipts. In short:

Two things can be independently true about social media. First, that there is no evidence that using these platforms is rewiring children’s brains or driving an epidemic of mental illness. Second, that considerable reforms to these platforms are required, given how much time young people spend on them.

This point is especially important:

Most data are correlative. When associations over time are found, they suggest not that social-media use predicts or causes depression, but that young people who already have mental-health problems use such platforms more often or in different ways from their healthy peers.