Bluesky posts have a rich text system, which means links in posts are similar to anchor tags. It’s not a markup; it’s a way to annotate slices of a string with facets such as links or bold or etc. This means you can linkify any text, thus the first concern raised. We intend to create an interstitial warning if the linkified text doesn’t show the domain clearly.
The posts also have an embed system for images, links, and other posts. We currently naively accept the link cards as published, and we need to stop doing that and fetch the link cards on read instead.