GFX isn’t even a term outside of the Roblox world.
GFX stands for Graphics and really has no meaning in the real world. It simply sounded cool and someone used it in one of their portfolios. People saw it and thought it sounded catchy, so more people started using it. Now we have you two arguing about what GFX really is.
Furthermore, the term “GFX” was created for professional renders inside of Blender, not for a Studio screenshot.