I love how some folks in this thread tried to make others feel stupid for thinking this is a peephole. The fact that it's being dismissed by some is ridiculous. Here are the facts: there's a sizeable hole above a toilet in the ladies room that's large enough to see movement on the other side of the wall, and it hasn't been fixed in weeks at least. You don't have to argue whether the hole was made intentionally to know that it can still be used as a peephole with various types of cameras and likely the naked eye. It didn't have to have an intentional creation to turn into a peephole. My guess is that many holes are discovered in conspicuous places that just seem to be the perfect place to get one's perv on.
That said,
@lazyboy97o is right on target. Even if tile cracked and fell away due to the close grout line, there's still board behind it. Even if the tile broke and fell off and the board behind the tile got wet as some suggested, wet board doesn't just fall away without help. Someone would've needed to assist the removal of material at that spot. The first hole in the wall for bolts is located at least a couple of inches below where the "peephole" is, so it wasn't an inadvertent hole in the wall due to the sinking of the height of the toilet. The wall is solid behind a wall mounted toilet with the exception of the holes for the bolts that hold it to the wall, the hole for water supply, and the hole for drainage. There isn't a toilet shaped hole in the wall behind the fixture so if it sinks it exposes a giant hole in the wall.
My personal opinion is that it may have started as disrepair with a cracked tile, but I think someone may have decided to take advantage rather than repair and created the hole where the tile broke away. I've ripped Disney left and right on these boards recently, but the creation of this situation isn't Disney's fault. It's an issue with humanity in general. Disney's fault in this situation is that maintenance and quality checks are so off the radar that these things can happen and they don't get noticed for weeks if at all.