Why do you believe that what you are presenting is malformed? When you see:
[![enter image description here][3]][3]
This seems to be the new behavior of the image upload/insertion tool and it makes sense. Here is the breakdown of why:
Previously, an uploaded image would simply be:
![enter image description here][3]
And while you were able to see that image, you could not click on it. Might seem like a small issue, but some users upload images that are quite large and hard to read at small sizes. By being able to click on an image, one is able to effectively “zoom” in on the content by downloading the full image read it better.
So since the image upload mechanism basically relies on a URL connected to Imgur, by wrapping that image in the URL reference ([][3]
) like this:
[![enter image description here][3]][3]
The image becomes clickable.
I am not too sure when this specific feature was rolled out—this Meta Stack Exchange thread and this comment refers to the change but no clear date of roll-out—but as your screenshot shows old images that predate this change are still in the system. I don’t believe Stack Exchange does a database sweep to cleanup things like this because it could be a messy proposition; while some images would benefit from this click-to-zoom/download others gain no benefit and might go against the original poster’s intent.
So nothing is malformed. It’s just slightly different and—in my humble opinion—much better now.