I am trying to model a snooker table for an Unity game and I have an issue with strange shadows on the cushion:

This is how I modeled the curved edge:

It's not an Unity issue because if I choose smooth shading on Blender, I get some strange behavior too:

I tried to recalculate the normals and I also checked if the top vertices are on the same plane and they are. Am I modeling it wrong?
