I would caution against reading too much at this stage, even though the researchers were very careful to talk about only correlation, a lot of people here seem to read causation. This are population studies so the variables are not independent.

The argument became a bit unpopular because it has been (ab)used by smoking companies and gambling establishments but while an addictive substance can addict anybody, who gets addicted is not random. Watching of TikTok reals is a time wasting and dopamine inducing behavior - while I don't doubt they are bad and I avoid them, you may also be selecting for depressed or lonely people.

This I only write because people sometimes get in to an obsessive social media cutting frenzy spending effort that would improve their lives much quicker spent fixing diet or exercise.