Manchester City have a really tight fixture lately. They have another PL match to play in 2 days and only 3 days after that one they are going to play the first leg in the Champions League. Guardiola has a really tough job to do truthfully. Because they are in a fierce fight for the PL title on the other hand. He can't just do a big rotation as a result.
De Bruyne and Haaland were rested in the Aston Villa match. However Haaland's rest might have a different reason. His form has dropped a lot lately as you know.

I really wonder who we will see there in the first leg, Haaland or Alvarez?
Last match Pep Guardiola success make rotation after winning over Aston Villa and next match Manchester City will make more than 80% rotation players because facing most weakness team Crystal Palace. Its not problem for Manchester City with three days left before facing Real Madrid in champion league match because Pep Guardiola have rested kevin De Bruyne and Erling Haaland will be fresh for facing Madrid.
Last premier league match against Aston Villa, Pep Guardiola rested many main players and seems against Crystal Palace have many players will put on the bench for facing Madrid. Its warning for Madrid although they have more day taking rest but Manchester City keep with the full players for first leg match except with Kyle Walker and seems Ederson still injury.
Guadiola will rest players in the league thing they face Real Madrid first, because Guadiola will not like to risk any players against Crystal Palace since they are a bonus game for them. I don't think Manchester City have any tough game in the premier league now again is just Tottenham and I believe Manchester City will still win the match. Manchester City will like to draw against Real Madrid in the first leg then they will finish the rest in the Etihad like they did last season. However, I believe Ancelotti will not allow that to happen this season since they have players who will perform well on the pitch and help the team qualify for the Champions League's next round, where they will face Arsenal or Bayern Munich. Before Manchester City face Real Madrid, I believe they will do everything necessary to bring Walker back because without Walker, I believe it will be extremely difficult if Real Madrid does not defeat Manchester City at home.