Of course Pep Guardiola is a coach with a new philosophy and has a broad insight into players. He installed Julian Alvarez in De Bruyne's original position. If you saw him in the first game earlier this season. Although at that time De Bruyne did play but in double pifot with Rodri. But it turned out that his hamstring had not healed properly and he only played 23 minutes. Against Newcastle, Julian Alvarez was back in the same position. Even he was able to make goals.
Pep Guardiola is a great coach with good ability for adaptation and he can upgrade many players by trying to use them at new positions. Dani Alves, Messi in Barcelona, Lalm in Bayern Munich, Walker, Cancelo, Stones and many players in Manchester City got benefit with Pep management.
Julian Alvarez does not have skills for an attacking player, a play maker like De Bruyne and he is more similar to Kun Aguero. Pep still has many players who can replace and cover De Bruyne such as Foden and Silva. He does not need to use Julian at the position of De Bruyne and I believe he knows the Argentinian player can not play well at that position.