Even normal kids will have a negative image of themselves. This is basically where anorexia comes from nowadays, perfectly healthy girls thinking they are to fat. The same effect is also seen in porn where expectations are just entirely different to real life, what you see is not always real and inexperienced women don't need to behave like porn actresses.

Social media I feel has a similar negative effect in expectations and feeling of inadequacy. Boys and girls seeing people's lives through an artificial lense, be it taking thousands of photos and only posting that one image that looks the most attractive or literally just photoshopping the "bad" things out. I always remind family members and kids of friends to not look at them, explaining(and in case of Photoshop demonstrating) how fake this all really is.

I am in no way surprised it helps kids mentally to not use social media. It's an utter cesspool and deserves to be brought to its knees finally. People ruining their health and life because someone apparently has it all better even though that's clearly BS.