Yes, it is definitely a disappointing result for Manchester City. Failing to hold onto their lead twice at home and allowing Brighton to come back into the game is a poor performance. Even in their inconsistent state I still expected them to secure all three points. Many bettors would have lost their wagers as City were widely expected to win. Dropping points in such games could hinder them from making a top four finish.
I think you are viewing Brighton in a different Direction, I will say you are getting it all wrong because no matter how popular the team is if there is no consistency they can face any defeat by any team no matter their class if they can prove themselves to be the best they can secure victory. I wasn't shocked about Manchester City's draw against Brighton because Brighton have maintained a very good performance in their last five matches by winning it all while Manchester City only secured two wins and three losses. I really don't understand Man City again immediately they try to show they are on a good track then you will receive the biggest surprise from them. Brighton are not consider as a bottom team compared to Manchester City because they are just two step ahead of Brighton.