It is customized. I asked our developers who helped with the customization to look into it and what they found (possibly) is that during the C/A update Font Awesome updated from 4 to 5 and in vs. 4 the gear icon is labeled fa-gear but in vs 5 it is fa-cog, but in vs 6 it's back to fa-gear. So css was added to be able to load the icon in either situation.
