Why and how would it be fake? I just went and looked on the Holocaust Encyclopedia and found many photos of that nature, photos which I won’t link or post here because they’re graphic.
But Dachau was not an extermination camp like Treblinka, Sobibor, Majdanec and Chelmo.
Why do you think that this is evidence that the photo was forged? The conditions in Dachau were terrible, they could’ve easily died of malnutrition, disease and abuse.
This photo has existed on the internet long before generative AI could make such images, though.