Had that happen with one of my spots. It’s just shitty concrete and unfortunately there’s not to much you can do once it hits the aggregate. You can paint it(I’d use rustoleum in the quart can and a roller not spray paint and do a few good coats, wax the hell out of it and go faster, or you could try mixing up some patching concrete and building it up again(haven’t done that so can’t say if it’d work or not). The repaint does work for a time but you’ll need to do it once it gets worn again.