"Social Media" seems to be a scapegoat for the underlying causes: children are in particular affected by this because they haven't had years/decades to build up mental disorders yet where they justify it to themselves that it's "okay", and the unfairness in the world through the lens of social media, taking the emotional toll head on. Children are very sensitive to their status in society, but we forget this because we grew out of that. Those of us on the successful side of things anyway.

Social Media isn't the boogeyman. It's that no matter how hard you try, your life will never be as good as what is usually portrayed through these channels. You are swarmed with people who lead far better lives than you do, have way more fun than you do, and so on and so forth. Your only escapism at home, in a pandemic, is to go on the internet where you're spammed with these successful people (posers or not, doesn't matter) selling you things by showing off what they have.

So no, it's not social media that damages teenagers mental health. It's worse than that. Ignorance is bliss? There's an argument to be made for that.

It starts before they even hit teens. That YouTube channel of the kid unpacking toys and other things is the kind of early stage precursor to things to come. The kids watching this viscerally live through him for some years, until it dawns on them that hey, wait a minute, he has all those toys and I don't have anything.

It's no wonder exercise makes things better - it's a great distraction from the illnesses of the world. Assuming that children are somehow not aware of it, or are not susceptible to it, is being naive at best.