Here’s the mesh.
Here’s it with subsurf.
So, why is this happening? I went out of my way to manually join the mesh as to create quads. Sure, it’s a funny shape. I can see how the right angle kind of looks whack, but conceptually, it’s all quads, right? I want to know the technical reason it’s not smoothing this over if possible and means to achieve this if this is not the correct way to go about it.
1) I deleted the inside faces 2) I merged by distance