I think social media probably isn't great, but the data also isn't particularly conclusive, and much of it is very broad and unhelpful. For example, in the first study you linked, it had a sample of 143 University students accross three different social media sites, measured only using app battery usage. While it isn't to be completely discounted, esspecially alongside the larger body of work, it's sample size is tiny, and the data collected isn't esspecially representitve of what is supposed to be measured, as it includes non-social-media tools like Facebook Marketplace while excluding social media accessed via the browser (among other flaws). The vast majority of studies on the topic, regardless of findings, have similar flaws.

IMO, social media as a whole is too varied to meaningfully lump together, and a lot of the impacts that are commonly attributed to social media are better attributed to deeper causes regarding lack of sociatal trust and support. Tracking the impacts of social media is hard enough, nonetheless the impacts of something like the lack of third places, and impacts of economic inequality on mental health.

Social media takes hundreds of different forms (including e.g. Lemmy) and any study pretending that they're all the same is useless — unless you can simply replace "social media" with "Facebook", "TikTok", or whatever they're actually about.

For example the first of the studies linked above finds that using "Facebook, Snapchat, and Instagram" more than they normally would makes people depressed, and the second finds that an unspecified mix of whatever people normally do that they think of as "social media" did not. Those findings do not contradict each other and do not represent a meaningful controversy.

Politically it's a controversy, or a tangled mess of controversies. Scientifically it's just a complete mystery that will — at the speed of science — take decades to unravel. With any luck all the findings about fucking Facebook and Twitter will be obsolete much sooner than that because at some point the enshittification will finally get so bad that people come to their senses and stop using them. The free-world versions of social media, such as the fediverse, continue to get better and will win in the long run.

Just based on my personal vibes, I think social media is harmful if you’re doing it wrong. Most people are. If you allow Meta to manipulate your emotions with fear and hate, while developing an addiction at the same time, you’re not going to have a great time. Quitting that kind of toxic relationship will improve your life.

Mastodon was designed to be less addictive, and that’s why it’s a bit boring to most people. It takes special kind of dedication to get addicted to Mastodon, and I think the same applies to Lemmy as well.