Has there been any further detail on what about social media is linked to depression? For instance, with Facebook, is it more because of the ads? Or is it more because of the engagement algorithms? Or, would it happen even if Facebook were just a reverse-chronological feed, populated only by your chosen friends, with zero advertising?
Binging TV shows, binging Facebook, and binging internet usage in general are all highly correlated with depression.
With correlation, it's important to remember that causation doesn't necessarily flow in only one direction. It's likely that depression causes increased sedentary activity, including Facebook usage. It's also entirely possible that social media usage encourages depression by displacing more productive, healthier activities.