By default Danbooru has a feature where normal users' uploads need to be approved by a moderator or admin.
These uploads have a blue border around them.
On Danbooru, this is useful because this way mods or admins can delete "incorrect" pictures without having to hunt them down as they are neatly placed in a dedicated page.
On One Yukkuri Place this is less useful, since as long as it's Yukkuri it will be approved; there are very few exceptions to this norm.
The "upload volume" is also way less than on Danbooru, so admins can simply check the main page to see new posts.
Basically, the blue border is just a formality.
However, because this feature is an integral part of the Danbooru software, used in a modified form by One Yukkuri Place, it can't be yanked out without breaking the whole thing.
As long as a mod or admin approves your post within a set interval (should be about 24 hours), you don't have to worry about anything.
If your post hasn't been approved despite being Yukkuri, contact a mod or an admin.