This is one that I tried my best to find a good balance for. Lemmy doesn’t support marking a post as a text, media, link post. So, if a posts primary url is not a media link, the media will not be displayed in the feed. However, if the primary url is a media link, and the post body contains media URLs, then it will be displayed as a gallery.

Arctic used to render all posts with media as the primary URL, or media URLs in the post body as media posts, however there were a lot of instances where this was undesirable, so I changed it. I’m hoping in the future, Lemmy will support tagging image groups as gallery’s, and post types, eg: text, image, link, etc. in the mean time Arctic just tries to make a best guess. That said, I am going to look into rendering posts such as the one you linked as image posts, in the case that the entire body of the post is a media URL.

I hope that clarifies this instance, but I’m definitely open to feedback on this behavior.