I would have guessed that this was an authentic photo based on them showing up correctly in the mirror. Can AI image generators handle mirrors? That would be seriously impressive to me.
Proooobably not yet. Apparently Midjourney (one of the better AIs for humans) no longer has a free trial, so I can't test it myself. But I tried to search and there doesn't seem to be much suggesting it can pull off a mirror realistically.
Though with how much it's improved in just a couple of years, I'm sure it's not far off from being able to.