Thanks to various chemical factors, the burger and fries still look the same as they did when they were made, almost 2000 days ago.
Hopefully something will happen eventually, like a little bit of fungus or something. Check back in a few decades.
Or you could make a pilgrimage to Utah and see the world's oldest hamburger, which has been going strong since 1999.
The fast food giant has previously attempted to disprove experiments like this, actively advertising that its food rots.