I believe that the problem of plus-size discrimination based solely on the number of square inches of skin has been verified. I remember reading about a community that objected to a swimsuit photo of a fat model in a store window, that thought nothing of an average size model in a bathing suit that was far more revealing than the fat model, but showed less actual skin area, due to the fact that the model was slender. That happened in Long Island, NY in the 1970’s! I am sure that it is commonplace. Unfortunately, whomever programmed the AI used by Meta must have fallen into the same trap.

Also, I believe that much of the stigmatization of fat people is due to esthetics–some people feel threatened when they see a person who takes up more space, and more threatened if the person they are looking at are conventionally attractive, except for being a larger-sized version!