It “leaks” which apps you’re using if the developer explicitly talks to the discord client. Discord provides an SDK for game developers etc which can talk to discord client and show the game you’re playing and optionally let you invite people to your lobby straight from the discord chat. It doesn’t scan anything or open any processes, it just opens an IPC socket.
I think it does scan your processes. If I go to "User Settings " => "Activity Status" => "Not seeing your game? Add it!" => "Select" then I see many processes that almost certainly have no explicit discord integration. I believe they do this to allow the user to opt into showing their status based on running processes so that any application can be supported.
Yeah, it scans processes but seems to limit sharing what you are running to what it thinks are games unless you explicitly add the application. Still, anyone concerned about privacy should really sandbox these proprietary applications or just use the web version.
