Your title here isn’t technically wrong, but it is misleading. It should be "white AI faces judged to be more real than white human faces. The way you phased it insinuates that white AI faces are judged to be more real than a diverse mix of human faces.
For anyone who doesn’t want to read the paper, they basically took an 60 white men and 60 white women, and showed them a whole bunch of white faces, half of which were generated by AI. It turns out that AI faces were rated as more human-like than actual humans, and they had some hypothesis why. Principally that AI, by its nature, generates images close to “average”, while real people tend to have features that are not “average”. The reason the study focused on white people is that most AI have been trained on white faces, so AI tends to do better with white faces.