Material color changes slightly during export

[markus-senger]

When a model is exported from Unity to the glb format, it seems that the material color is automatically slightly lightened.

Example:
The following model is being exported from Unity to the .glb format:

the following shader with the following material color is used:

In the next step, the model just exported is imported back into Unity, but the material color is slightly altered:

The issue occurs regardless of import during runtime or design-time.

• glTFast version: 6.2.0
• Unity Editor version: 2021.3.4f1
• Render Pipeline and version: Built-in
• Platform: Editor

export code:

          var exportSettings = new ExportSettings
          {
              Format = GltfFormat.Binary,
              FileConflictResolution = FileConflictResolution.Overwrite
          };
          var gameObjectExportSettings = new GameObjectExportSettings
          {
              OnlyActiveInHierarchy = false,
              DisabledComponents = true,
          };
          var export = new GameObjectExport(exportSettings, gameObjectExportSettings);
          export.AddScene(new GameObject[] { exportObject });

          bool success = await export.SaveToFileAndDispose(metaDataHandler.pathCAD.Replace("_cad.json", ".glb"));

import code (during runtime):

        try
        {
            success = await gltf.LoadGltfBinary(
                                            data,
                                            // The URI of the original data is important for resolving relative URIs within the glTF
                                            new Uri(orgPath),
                                            new ImportSettings()
                                        );
        } catch(Exception e)
        {
            success = false;
            UnityEngine.Debug.Log("LoadGltfBinary failed: " + e.Message);
        }

        if (success)
        {         
            GameObject model = new GameObject("ImportModel");
            model.transform.parent = cadRoot.transform;
            await gltf.InstantiateMainSceneAsync(model.transform);
            ...