Pride cape texture, issue with the triangle

Steps to reproduce
Just see the pride cape
Observed results
The triangle is less even not textured compared to the rest of the cape and also the transition between the front, the side and the back isn't smooth.
Expected result
The triangle should be textured like the rest of the cape and the transition between the front, the side and the back should be smooth.
Example (not perfect but you can see the problems with the actual texture) :