favicons are a pain, coming from a part-time web editor. As has been stated, 16x16 pixels, and that's not a whole lot of room for what most people think of as an "icon."
A customer recently asked why HE didn't have one. Asked me to make one "from our logo." Hours of work later, I bill him for a tiny portion of the total hours for what he calls "two measly triangles." Yeah, I'm a big fan of "favicons" :/
I am not a digital artist 😀