The link has no images, nor is the image in the project file available.
“WhatsApp Image 2019-12-03 at 13.01.23(1).jpeg” is missing.
You might know it, but just in case, to include content like images, the project needs to be saved with assets.
Main Menu> File> Save With Assets…
Please have a look at the Image:
You can see clearly, that the Spline Shader isn’t sitting correctly (I assume…), I copied and pasted the Shader into the luminance Channel to show the effect.
In the file below, I centered and scaled it up. Besides that, the Displacement was set to Intensity Center. This means white goes in one direction and black in another. Since the Shader produces a lot of blacks, anything besides the white stripes is displaced as well. Set to Intensity, black has no influence, and only white is displacing the surface. I set the caps to regular grids.
The Spline Shader is square, and it is looking at a Spline from this square. Which means that any width of the spline is related to this. While projected as Flat to the object, it is stretched to cover the Rectangle shape. This stretches the lines. My suggestion, use an image for the Displacement. You could render a top view of the object and work on that in Ps.
Perhaps modeling that shape is faster. Example screen capture is here
Note that I reduced the size first, to extrude it later. As I often mentioned in this forum, it’s like playing chess, think about a few steps ahead.
Please note that I have set up the Loft with no Start Cap, and changed the Subdivision U as well as the Cap Grid. IF the Start Cap is on the same level as the End Cap, you might experience problems during rendering.
Let me know if there is any other question, I’m happy to look into it.