Variable Mix Shapes stretches faces

[GameDeveloperek4123]

Hi, I have a problem with Variable Mix Shapes. I'm making Generator for railroads platforms using Shape Extrusions. I want to make one that's wide at start, but ends narrow, so I divided my spline on three parts - wide, Mix, narrow. But it doesn't work right. Here's how it looks - first screen is from the wide part, second from narrow.

   
   

Not only it breaks UV's but also geometry:

   

Here's the shape of platform:

   

For narrow shape I'm using the same shape, modified by TRS Shape. Tried to do it with separate shape but didn't change a thing.

   

I'm really sorry for the mess in my nodes


I'm using:
Unity 2022.3.20f1
Curvy Splines 8 ver. 8.9.2

Can someone please tell what I'm doing wrong?