Looks like a test instance. URLs are read from the end to the beginning, so enterprise.lemmy.ml is a domain controlled by lemmy.ml. As that is the instance that the main developers control, it would follow they have a testing environment. In addition. Almost all the posts, users, and communities seem to have “test” as part of their name. It being the instance controlled by the developers is why lemmy.ml is always a link, while lemmy.world would need to be formatted as a link to get a link.