Smooth Lighting Mirrored on some Block Models

At specific block models, like stairs or slabs, does the smooth lighting seem "mirrored", causing sharp edges. If you look closely at the stairs on the image I attached, you can see the smooth gradient mirrored of how it should be. It is more clear when using a texture pack. This is not only the case when using stairs, but also slabs, tree logs, quartz pillars and actually almost every block except the normal block model.

Smooth Lighting has been set to "Maximum".