Just sharing a shoe dye which worked quite well. Unfortunately the before and after pics are taken in completely different lighting conditions so they don't show properly how deep the brown is after, I might take another new photo tomorrow.
My tips: Wear thin
plastic gloves as it will stain your fingers, cover the work surface and use an artists brush not the
one they supply. Doesn't work on patent or gloss leather (special
finishes) but worked great on my slightly tired medium tan shoes.