Tbh it’s more like an edge-lit acrylic effect. We did call it a “subsurface effect” when I worked at Forza but may have been using the term loosely. Forza also was going for acrylic rather than glass and we had several acrylic samples around the office to play with.

That being said my example is not acrylic… and it’s not quite glass either as you mention. It’s more like glass with some artistic license.