Baking node normals doesn't work?

So in this first image, I made some a normal map with this simple node setup :

Which produced this :

At this point, I thought to speed rendering up, I’d bake the normals. And while
the render sped up, I have this problem now.

And I’m honestly baffled by the artifacts. Note the ‘edges’ are actually where the seams are,
but should that produce this kind of artifact?
Please someone tell me what I’m doing wrong.