Both saved posts and saved comments are mixed in together in the "Saved" feed. This is how it worked previously when the "Saved" feed was in the profile, too. If this isn't working properly and you don't see your saved comments in the "Saved" feed, let us know.
In future, we'd obviously like to add more granularity here, such as being able to filter the saved feed by just posts or comments, or sorting the saved feed.
Spoilers, subscripts and superscripts don’t work, but everything else does.
Markdown in general is unfortunately rather difficult to render. We use an open-source treesitter that parses GitHub-flavored markdown, which is similar to Lemmy’s markdown. Fully supporting the Lemmy markdown specification (spoilers, for example) would probably require us to instead use a custom implementation built directly out of cmark.