Discord seems like the major social media companies to me. They apparently keep everything you've ever posted, and I've no doubt they sell or otherwise commodify user data. I recently requested my data, and the description they sent with it said that it included everything I'd posted.
I deleted Discord, and I'm on Mastodon now. There's no centralized company running it (individual people set up their own servers), and a lot of these individual "instances" are intentionally set up to keep out trolls and abusive people. But it is more like Twitter than like Discord, and the moderator can see everything you post.