Walker is wanted by both sides (City would probably not mind keeping him but would also be happy with letting him go out of respect), whereas Cancelo is not wanted by City and Bayern doesn't want to pay the fee that City wants.

While he has made it known that he isn't happy with his reduced minutes, Walker has got his head down and stepped up when Pep needed him. Cancelo on the other hand, has kicked up so much fuss to the point where he doesn't have a future at City after being the defender that played the most. Pretty different situations here I would say.