No, it is “Top surface”. Toggle the Display check marks.
Changing Sparse Infill changes nothing.
Turn off Top surface and you see the underlying Internal Solid Infill.
No, THIS is the original question:
There is no “exposed section”.
An exterior face may be a wall or a top surface, the difference is only the orientation, which you are unwilling to change. The visible portion of a wall is mostly the side of a layer, the visible portion of a top surface is mostly the top of a layer.
Since you apparently have not attempted an actual print using the recommended orientation, you are trying to correct a “problem” that is only in your mind.