I'm not a PGMOL apologist at all as you know, but I tried a while ago to explain what I think happened.
To summarise, he expected a game between two evenly matched teams playing the same sort of game, so he decided before the game to let things go in the expectation that he could do the same, consistently with both teams. His problem was that he didn't read the game. It was clear pretty quickly that it wasn't City vs Arsenal of last year, it was akin to City vs Brentford. He didn't realise that quickly enough, if at all, and so he mismanaged the game. Probably why he handles games either well, when he gets it right, or loses control of so many games, when he doesn't. Not understanding a game isn't a good look for a referee.
I don't believe for a minute that he was out to "get" City. That job is done. The PL has its title race and will have now to the end of the season. No need any more.