This always comes up about McDonalds food, but the question is what are the environmental conditions where this picture was taken and the food was stored?
If the food was properly desiccated it could stay in this mummified state indefinitely.
If the Pharaohs ate McRamses Burgers people would blame them for the fact they are so well preserved.
If they really wanted to show this effect is genuine they would buy multiple burgers from different burger joints and have them all set side by side for years, there is no "control" for this picture.