Align the normals or what am I doing wrong here?

Using my own function, I triangulate paths of different lengths. Now it happens that the triangulation is calculated in opposite directions. Is this the reason for this optical error? Or do I have to reorient the normals somehow?

Could you do a repro in the playground with fewer lines with fewer points. This is often a good ploy to list VertexData. It could be that triangulations are orientated (clockwise or counter clockwise) differently.

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The playground could take a little longer. I have to see how I can get the data into the playground.
The triangulation of all triangles is counterclockwise (front face and back face).
The triangulation is similar to the ribbons with the difference that with different path lengths, triangulation is also used. This is probably where the error lies. But what is the connection between the triangulation and the normals to cause such a graphic error? Does it matter whether 4 points are triangulated from top left to bottom right or from top right to bottom left?

The marked positions are triangulated like all others in a counterclockwise direction.