(For the record, I don't consider IM clients, website hosts, or art sites to be social media.)
I only use Tumblr and Bluesky right now. I left Twitter 2 years ago and had a bad time on there anyway, and I was suspended from Reddit after using a VPN and can't remake accounts without getting auto-suspended. I'm not comfortable using Facebook and Instagram because it's too tied to my real life and I don't have any non-familial contacts IRL. So these are currently the only two mainstream sites I use. I'm not super social on Tumblr outside following blogs, and it's the only social media where certain mutuals are on. I'm unfortunately weirdly addicted to doomscrolling it. Bluesky I started using last spring after going to conventions, it's my one mainstream site. But I get addicted to scrolling that too. So I need to detox at some point. :(
I GUESS I also have Dreamwidth, but it's not touched as often because... Well, few people I know really use it. I should probably switch out sites at one point though, like focus on prioritizing DW for more "slow burn dopamine" or whatever. My Insanejournal and Deadjournal accounts are dead because even less people use it than Dreamwidth.