Short answer: Discord bad, use Matrix
Long answer: Yeah, Discord is not great for many reasons. The video on first glance seems very clickbait so I won’t really comment on it. But Discord effectively has no privacy would be the biggest reason to avoid it unless you have people who really don’t want to switch away from it. The desktop client is yet another shitty electron app and they lagged behind the current electron version for a while too with all the bug and security implications thereof and the UX is just not great with all the little pushes to spend money on a premium subscription.
And yeah, big Tencent investments, but pretty much everything gaming-related is in that same shit so.