Well, tencent did make a sizable investment in Reddit a few years back.
https://time.com/5526128/china-reddit-tencent-censorship/
But then again r/fuckthecpp was a pretty active sub that received pretty much no censorship from the CCP as far as I know.
I try and avoid Discord though …they farm way too much data. I use it only when co workers insist on using the platform, but I always begrudgingly mention Matrix clients like Element instead.
You can open up ublock origin, noscript, or even just your network manager in your browser’s devtools console to take a look. I just remember it being a lot.
The YouTuber trafotin does a good job showcasing how to best harden it, but unlike most sites, discord has made their app unusable unless you allow pretty much all of their trackers through.