I remember one thing about a rerctangle that was divided into triangles and then put together resulting in a thing with area less than one. The thing was, the angles of the triangles were different, they were so small they were barely seen (on PC), hence the error. Here it’s most likely the same, with the pattern on the triangular parts made in a way that when combined in a proper way it creates illusion of 3 more squares, and the rest is wrong angles.