Yeah this happens pretty often, though I'm surprised it continues with Font Awesome's organizational changes: The "fab" prefix is specifically supposed to communicate that it's an icon from the "Brands" style. (Non-brand icons use "fas".) If you find yourself using a "fab" icon generically, you might want to double-check what it's supposed to represent...
Honestly, a lot of times when I'm doing quick designs, I just open the font page with all the images and just visually pick any that looks best. Definitely needed some sort of legal pass before release.