Ellipsoid Graphics Flat Shading

I am using EllipsoidGraphics to draw beams that have a value that determines their color from a color gradient. I am having an issue where two beams with the same color value will render with visibly different shades because of lighting effects.

After setting shadows: ShadowMode.DISABLED on both the EllipsoidGraphics and the Entity that contains it, I can see these lighting effects are still happening, which means it must be caused by the distance to the light source rather than the shadow of the globe.

I can see that both EllipsoidSurfaceAppearance and MaterialAppearance allow for a flat property that seems to be what I need. My issue is that neither EllipsoidGraphics nor the container entity has no appearance property to set.

How can I get flat shading for my EllipsoidGraphics? Is there no way other than rewriting the entity as a Primitive?

Any help would be appreciated, I am still fairly new to this so apologies for any incorrect terminology.

Edit 1: The only fix I have found so far is to set the intensity of the sunlight to 0, like so:

const sunlight = new Cesium.SunLight({
  color: Cesium.Color.WHITE,
  intensity: 0.0
viewer.scene.light = sunlight;

The issue with this is that all colors are now darker, as if they are all under a shadow. Is there is any way to just show the actual css color I am trying to show, with no lighting effects?

Yes, it seems that re-writing that entity as a primitive is the only way for now.

Let me know if you got other ideas, I am facing a similar issue.