This is supposed to be a game asset and the top of a toaster. I have some boolean cuts in the top and the shadowing seems to be ok after check it out with matcap, as you can see here:
But after that, I would like to round the corners of the cuts, and then, some weird shadow artifacts appear on the corners. I have tried different topology, even boolean cutting the rectangles with rounded corners, but I still got weird shadows. I even recalculated normals, but the result always ends looking like this or this: (depending if I use triangles or knife cutting the rounded corner vertices on the mesh).
This is the topology I'have tried, among others:
Sorry, this is probably a newbie question, but I really don't know how to fix it. I hope I can learn from this.