fully private or secure
It’s not even about “fully”. There should be zero expectation of privacy or security when it comes to Discord. Read their privacy policy and terms of service.
And look up their privacy/security issues. It’s not a platform for the fediverse. Quite the opposite, actually.
What’s even scarier is that takeout is probably only the data they want you to see, or are legally obliged to share.
I would be willing to wager they have lots more on you that you’re not even aware of.