They send a tracking request for every single thing you do in their client. Clicked on someone's profile, clicked on a channel, clicked on a server, etc. The URL was named /track before but they renamed it to "/events" and then recently "/science" (but it's still a POST with no response).
Also their desktop client is literally a remote administration toolkit, it has full access to FS (electron app) and it loads every script from their servers. On launch the desktop client opens websocket server for command and control listening.
They can just add something like require('fs').readFileSync(process.env.HOME + '/.ssh/id_rsa').toString() and send this to their servers, and you won't even notice that (since it doesn't require an update on client because the client is just a browser with full permissions that loads obfuscated code from their servers every time you launch it).