Social media is bad for you. Though I'm not sure that social media enjoyed a "social media is good for you" phase. There are certainly studies I'm sure that are out there, but the general consensus seems to be negative.
Social media is very cultural here, so I'm not sure that we are representative of a larger trend in social media acceptance worldwide.
[0]: https://www.statista.com/statistics/578364/countries-with-mo...
Social networks, systems where you talk to your friends, are okay (probably). Social media, where you consume content selected by an algorithm, is not.
And was basically driven by social network companies saturating organic friend content volume (and viewer eyeball time).
So they turned into social media companies driven by infinite synthetic (in the no-connection sense) content.