What you are experiencing is due to the fact that the first segment in the Follow Me path is not perpendicular to the profile (or the ground plane in this case) The Follow Me operation projects the profile to be perpendicular to the first segment in the path. The end face of the extrusion will be perpendicular to the last segment, too.
The fix is to not draw an arc for the path but instead, draw a circle and split it at the mid-points of sides at the correct angle.