@futureisfoss DMs are a complicated topic.
To answer your first question, no, they are not end-to-end encrypted.
The second answer is even worse: They aren't even necessarily direct. There are platforms that will just show them publicly. Mastodon definitely handles them properly, but nothing prevents them on other platforms to be published.
Therefore do not use them to have private conversations. Use a platform like Matrix or Signal for such conversations instead.
I know that there's benifits of using mastodon, most of which are related to decentralization (preventing censorship, excessive data collection, ads etc.). But I consider e2ee as pretty basic these days, and I expected DMs to be private.
This is my personal microblog. It's filled with my fun, joy and silliness.