This research is highly debated and is by no means a sure thing. The research so far has been correlational, inconsistent, and weak. Twenge
hugely overstates the confidence we should have in the findings.
See https://medium.com/@OrbenAmy/social-media-and-suicide-a-crit... and https://twitter.com/shuhbillskee/status/955070356091555840 for some critiques of the work.