Weird edges with solidify and subsurf modifier I am making a model of a ferrari 458 and and currently I'm facing a problem I can't solve. When using the solidify and subsurf modifiers, the areas where the mesh is connected on the diffuser have creases. I have tried rebuilding all the area from the beginning, smoothing the vertices, faces and edges and merging by distance, but nothing worked as intended.
Any thoughts on this?
You have inner faces, what we see is the shading between the outer and inner faces. If I select these faces and hide them:

I can see this face:

Delete these faces.