Lastly, the links inside the body show only on one of the cross-posts, but the ones outside the body show on both cross-posts.
The outer list is automatically generated and every post to that link will appear in this list, even years later. Its pretty cool, but nothing new, we had that back in Reddit too. When Reddit existed. The post content is just a link added once. When I do a crosspost, then the content of the original post is added automatically too. This is only one source where the original post was shared from, and will not automatically update (unlike the above outer list). I assume it depends on the software they are using, when generating the crosspost. The post body is managed by the user and the app they are using to generate the content, which is a normal link to the web like any other. The above list is managed by the Lemmy system and out of our control. So it can do the optimized linking with short style automatically.
This is actually one of the reasons why I don’t like the way some do their posts (I don’t mean cross-post, but normal post). Instead a link to the article or whatever they are linking, an image is uploaded, and they link to the main article in the body text. This will prevent the Lemmy system from automatically connecting all articles. So it does not matter if the post is shared with cross-post or created from scratch, if they link to an article with the same address, then the Lemmy system will recognize the same article and connect them in the outer list, across all Communities. I really love this feature!
I’m glad this helped in understanding. And also thanks for updating the post.