The color effect looks like this might, under the hood, be the same as what is reported in Brown metallic reflection and tracked in New 1.123 Environment Map Rotates Together With Model · Issue #12310 · CesiumGS/cesium · GitHub
The color effect looks like this might, under the hood, be the same as what is reported in Brown metallic reflection and tracked in New 1.123 Environment Map Rotates Together With Model · Issue #12310 · CesiumGS/cesium · GitHub