"clear shadows come from sunlight or powerful artificial light"
Shadows are a matter of size (relative to the subject) and direction of light, not intensity. Small light sources will create deeper, sharper shadows. Larger ones softer shadows. Frontal lightning will remove most shadows, as they will fall where the imaging sensor can't see them. But flat lightning is common in amateur flash snapshots and paparazzi images, while most photos will have some shadows (high-key images have little or no shadows but are a very different kind of lightning).
IMHO, without an algorithm which includes lightning information, an AI will discard shadow information when it gathers faces features, and then will have to create an image without them. Anyway, it would probably need a 3D model of the face to apply shadows correctly, and probably this isn't generated, albeit an approximation may fool most viewers.
If the fake images were compared with a flat-lightning real image, it would have been more difficult to spot them.
Another hint is the lack of background, evident in the first photo, less in the second, where there's still a slight fall-off as the light comes from the left, while both fake photos have very simple backgrounds, as it's easier to synthesize them. Again, putting the image on a realistic background would make them harder to spot.
The woman face is interesting, because it's not symmetric enough, and the lightning highlights that.