I'm a millennial, so I can't really speak for zoomers. But to speculate, I'd say that a lot of people are on discord because if you play video games, you're probably on discord to socialize and/or to use the audio/video chatroom stuff when actually gaming. But the reddit thing seems more like a "lifehack" content thing than anything else. I doubt many people saw that tiktok and created a reddit account because of it, which is what I consider "using reddit". And 100k seems like a lot, but couldn't that just be all the reddit users who also use tiktok?