@Admin I just encountered it again, in the post at https://startrek.website/post/2041553 Clicking on the link in the post is OK. Clicking on thhe thumbnail, though, delivers the JSON in a new window.
@ValueSubtracted I don't know if this is just my instance (mstdn.social) or what, but for the last few days when I click a link in a post from startrek.website I don't go to the link, instead I get a JSON payload delivered as plaintext.