Are there issues with importing Vertex Color from Blender?

Have problem with Vertex Color.
Import my fbx model with param “Replace Vertex Color”, have simple shader “Vertex Color → Base Color”, and i have wrong color.

In mesh viewer with “Vertex Color” option have same problem.

I believe the color is not wrong, simply that the Unlit mode also display the specular reflection on top (see : Lit vs UnLit : why displaying the specular channel? - Rendering - Unreal Engine Forums ).

Try switching to the DiffuseColor G-Buffer in your viewport display. It should display the correct color.

Select “Diffuse color”, colors is wrong
maybe color in vertices must be in “gamma space” or sRGB? or somthing like this?

Did you try BaseColor instead ? DiffuseColor is probably not the good one.

Problem in “Gamma Correction”, if add pow(x, 2.2) all is fine.

Silly question but how did you get the sharp color for each polygon? In my case it seems that it is only possible to store one color per vertex and therefore it makes gradients like here.