When you use the GPU in the browser, you can only request the high performance GPU. It is up to the OS to grant it or not.

So maybe the author forgot to include the high performance request, or your OS does not give the high performance GPU by default (as it might be in eco mode). This behavior can be changed in OS settings.

I think neither. You need to configure windows to use the RTX with Chrome. Maybe something like in windows graphics settings, setting Chrome to “High performance”. A quick web search for "force Chrome to use dedicated GPU" should give you all the steps you need.