PBR diffuse color seems off

I’m trying to create models which follow a company styling guide. I’ve created a gltf/glb model with a basic PBR material:

"materials":[
   {
      "name":"freshgreen",
      "pbrMetallicRoughness":{
         "baseColorFactor":[
            0.8039215803146362,
            0.929411768913269,
            0.8039215803146362,
            1
         ],
         "roughnessFactor":0,
         "metallicFactor":0
      }
   }
]

For reference the RGB for that color is: 205,237,205 - or #cdedcd in HEX. Here the link to the google color picker with it set: google color picker - Google Search

I uploded this model to cesium ion to see how it looked and it’s a bit off from the style guide. It just looks a bit greyer or bluer. It’s hard to say what exactly- just not green enough?

I get that rendering is not really easy but in this case there is no other lights or environment so to speak of so I would expect it to match the base color factor pretty closely.

I compared the model in a few other viewers and they’re all a bit different really.

Here’s a screen shot for comparison across a few application including Ion

It’s quite clear from this screen shot that there is something not quite right.

I’ve tried tweaking the baseColorFactor to try and get it to render as I want to but I haven’t had any luck.

I know rendering is extremely complicated, however, I’d love to know why this is happening and if there is some way I can counteract it.

Whoops forgot to upload an example: here a box with the same base color set
box.glb (1.5 KB)