That's what changing perspective looks like, after winning six out of seven, and winning fourth in a row, neither fans nor players nor management, nobody really was as happy as the first times, but after losing this many games in a row, and having only one win out of thirteen games, they ended up having a blast after they won another one, which shows you how peoples perspectives could change as well. In the end, we are looking at something that is changing all the time, and that's the most important part without a doubt.
I can't remember whether they didn't celebrate their fourth title in a row, did they not? But yes you are right, the joy in Pep Guardiola's face was as if something big just happened. Very unusual as he is definitely very emotional during games and going beyond crazy and is happy when his team scores the sixth goal in a game, but this was different. You could see in his eyes right after the game was over and when he gave interviews that this felt far more special than usual. Indeed a unique and uncommon situation for the Manchester City coach who won it all. The opponent here wasn't Liverpool, but Leicester City, a team from the relegation zone.
But I think he was also happy about Haaland scoring a goal. I was aware that Haaland was having problems recently, but when I read yesterday that this was his second goal in fifty days!, I didn't know it was that bad!