Apparently a fan shaded the green witches face to make the movie poster look like the broadway poster. The actress who plays the green witch complained about it online, saying (among other things) that it “erased” her. While I did understand her point, I also thought at the time that it was an overly defensive response, and the worst possible take on something that was probably made by a loyal fan. Importantly, she later apologized for her initial reaction. I respect that. We all get carried away sometimes.

Sorry I haven’t provided any links. I’m at work.

Edit: just search “wicked poster controversy” and several stories will pop right up.

Edit 2: This seems to be a good one. It covers the bases well enough, while not going into exhaustive detail.