About Haaland in the Champions League, I can say that he has been quite impressive in this tournament also. He scored so many goals here last season. Maybe he couldn't make much impact on the semi finals and the finale but I can't overlook his overall effort just because of that.
Manchester City are playing great as a team. They don't rely on only one player such as Haaland. The semi finals and the finale were great examples for that. It is the truth that Haaland is an important piece of the puzzle. But Guardiola has a system working like a clockwork now. Even when Haaland isn't in-form the rest of the players can make up for that.
I just know every player in Manchester City has a role to play, Manchester City does not really rely on any player for victory to take place, I think this is one the secret for success in winning trophies. Haaland played major role last season for Manchester City in premier league and in Champions league though in the semi finals and finals game he could not score goal for Manchester city because he was thoroughly marked by the opponent playing against Manchester City because he was a threat to them.
It is true that in important matches such as the semifinals or the Champions League final last season, Erling Haaland seemed to disappear on the field and his role as the pillar of the team at that time was immediately replaced by other Manchester City players who had freer opportunities to score goals. I don't think it's a problem as long as the team can use every player available and actually I'm quite annoyed because Pep Guardiola very rarely changes his players in the second half. So when they should have had the opportunity to score goals through supersub players, they still relied on the players who were there from the early minutes.
I see many people who say Erling Haaland disappear in the field like you say, because they think Haaland is not suitable for the games against stronger teams and that's why people think Haaland is just a player who can have good performances against the teams with a weak defending system, while he is not because other teams usually focus on Haaland to make this player stop.
I have different thoughts in this case, when Haaland's movement is shut down by several marking players it does not mean he is not suitable to play with a big club, it's just that in this match Howe realized that if Haaland was left alone then Newcastle would face a lot of problems so Howe did some special guarding to Haaland so that every pass made to Haaland could be cut from the start.
His space was narrowed and his movements were limited which is why he could not perform more like before.
It doesn't mean he's bad because he still plays well, it's just that the marking done by Newcastle players is better which makes him frustrated in this match.