Arguably, Cancelo's been the most underrated City player by our fan base. Many seem to think he's upgradeable at LB because he isn't an *actual* LB and "can't defend". That's why people were desperate for us to sign a very expensive LB with one (!) cap for Spain. It's a silly take, but it's down to pre-Pep stereotypes about what a good FB is supposed to be.
In pre-Pep times, defending was done mostly in one's own 3rd and thus close to one's own box. In Pep's system, defending happens mostly in the oppo's 3rd and in the middle 3rd, where Cancelo's our best defensive player in terms of interceptions, duels, tackles, etc. People fail to notice Cancelo's defensive contributions in the other 2 thirds of the pitch because they reduce defending to blocking, clearing, tackling...actions in our own 3rd, in and around our box.
However, I'm not sure Cancelo's 'angry' celebration was due to the fans who don't appreciate him. It's probably related to his frustration from failing to score from so many attempts last and this season. His shots to goals ratio hasn't been good and is one of his weaknesses. This season, with the goal yesterday, he has already scored more league goals than last season and is venting his frustrations. He is angry at himself for failing to live up to his exceptional talent. Talent wise, he isn't worse than any FB over the last 2 decades, including the likes of Alves and Lahm. Few players are total footballers like him.