Why is my grouped symbology in ArcGIS Pro not the same in Map Viewer or Map Viewer Classic?

[Tori]

So in ArcGIS Pro I grouped two classes together so they would have the same symbology, but when I shared it to ArcGIS Online it shows as two  different classes instead of the one. Is there a way to grouped the two classes again in either Map Viewer or Map Viewer Classic?

[RussRoberts]

Grouped symbology is not fully supported in Map Viewer but its on our release plan for the first release of 2023.