What is not in doubt is that there has been a sharp increase in teen mental health difficulties in recent years: look at this 30% increase from 2017 to 2021[0]. This also coincides with a significant increase in social media use among young people. Correlation is not causation, but there haven't been many other theories as to what might be driving this change.
[0] https://www.cdc.gov/healthyyouth/mental-health/mental-health...
I'd also want to know where the funding for this meta study came from.