Color input/output problems

I have discovered a problem when I was using variables to dictate coloration for a material.

This was the default input that I used for this material, using the Dynamic Parameter node and a few other things that I experimented with:

R: 1
G: 1/3 (which automatically set it to 0.33333…)
B: 0
Opacity: 1 (completely opaque, and it’s a UI material so nothing should shade/brighten it)

When I tested it, the color is off. By a large margin. Here’s an image I made in paint to compare the color of this material and what it’s supposed to be.

This is extremely frustrating to deal with, because that it’s supposed to be UI elements and whatnot, which doesn’t get affected by light nor shadow unless we are talking about transparency.
I can’t have a dynamic material that would change accurately, and if I want to have the color change be accurate then I am sacrificing the ability to alter it.

I could make something in Paint that would be affected by transparency without having this kind of weird glitch, but I want to optimize my game.

This is because UE uses sRGB by default.
See this thread to get linear RGB:

The gimmick seems to only work with 0.5, because when I use a value of 1/3, it overdoes the shading.