At least as far as kids are concerned, current evidence does not readily support this common believe.
Sabine Hossenfelder writes: "The idea that social media causes children mental health distress is plausible, but unfortunately it isn’t true. Trouble is, if you read what the press has written about it, you wouldn’t know. Scientists have described it as a “moral panic” that isn’t backed by data, which has been promoted most prominently by one man: Jonathan Haidt."
Video for more insight, if you are interested: https://youtu.be/V95Vg2pVlo0