This is Where does the chat get the thumbnail on Wikipedia links from? turned into a bug post
Someone was complaining their head felt heavy in chat so I decided to link them to a possible solution:
The butterfly image is located near the bottom of the page; it is the image used for the Psychiatry portal.
There are also other unfortunate examples of image selection, e.g. Engineering.
The criteria for selecting images seems way off, why can't it just select it by the highest image as displayed; not the source image size? If it picked the one with the largest
width tag in the HTML, that seems like it would be much better. If it uses some Wikipedia API, is there some way to just look at the article's 'source' page to determine it? Does the one-boxifier go out to every image and examine it?