I don’t see why everyone hates the 12 cases, I’ve been using it for a week and love it so far. There’s no way the color is “painted” on. There clearly is a coating, as in my experience all quality leather has to protect it. The whole point of patina is it takes time, sometimes years for arguments sake. Now I’m no expert on leather, but there’s no way the leather is painted.
My saddle brown iPhone 12 (Pro) case was nothing at all like the one I had for my iPhone 8. The 12 case was rough, rubbery, and got worse. The 8 case was smooth, leathery, and got better. Others may have a different experience and of course it's possible they have updated the materials.