Displacement inverted halfway through object

Lately i have been noticing that, when using procedural textures, There is an imaginary line through the model. And where this line exists things seem to get wonky. In the attached image, I have just inserted a noise texture into the displacement. As you can see, at one poinjt in the image the texture goes from convex to concave shading. Anybody know why Blender is deciding to invert itself?

Displacement input no longer takes a value input, but a normal displacement input. Add a displacement node. Unrelated, but a linear color gradient will do a hard clip. Are you sure this look is what you want?