I have no idea why but they definitely do. It's a physical effect similar to withdrawal from alcohol, if I drink enough to get a hangover, I also feel anxiety although there's no practical reason for it. Same with scrolling through Instagram / TikTok or Facebook reels. I can do it for a while but pretty soon I get an increasingly uncomfortable feeling and have to stop. I never get this from reading or watching movies so there must be something in the dynamic of scrolling that induces stress.
It's probably because there's no coherent theme when you're scrolling through reels. It's just one random reel after another and after a while, your brain is like "WTF are you doing to me"? Not to mention that the content from each reel is rarely anything that will increase your knowledge level in a quality way or provide any lasting value whatsoever.
Not that doom scrolling it's good for anyone's brain but the algos push more of what catches your attention, even if thats bad. I mostly get pets and science stuff on YouTube or FB, overall it's a mood lifter, but that didn't happen until I spent a while selecting dislike on anything scammy/conspiracy and such. Youtube is harder to train. If its crap or you know it's a negative topic, reject it. I've had to give up on Spotify though, no matter how I try to show it my music taste adding liked songs, it keeps creating horrible playlists.