Phones are a factor, but social media is the pits. The more I engage with it, the worse I feel in general. It's a combination of endless advertising (whether via traditional ads or "sponsored posts") and endless rage bait.
Different platforms seem to optimize for different "mixes". On Instagram, everyone seems to be selling something. While Twitter is rage-bait central. Don't have enough experience with TikTok or Facebook to comment on those.