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.