Well, haven't you seen that so far Pep Guardiola has always tried to rotate, change the system, with various experiments. as far as I've followed, Pep rarely plays the same lineup in every match. except for the center forward. even if Pep applies the same pattern, there will definitely be one of the players who will be rotated or moved in position according to the coach's wishes. especially when De Bruyne suffered a long injury, Pep always changed patterns, systems and rotated several players. and when Haaland was absent, Pep started trying to implement the same pattern for his squad. even then, several players suffered minor injuries. I try to interpret according to my personal version, if Pep is actually trying to develop the potential of some of his players.
Honestly, I can't guess what Pep Guaridola actually did. however, it is very likely that he is actually planning something, one of which is finding the ideal player composition which he will apply later, especially if the main players leave or are injured. So referring to what you said, it looks like Pep has been doing it since De Bruyne was injured, and that's apart from the new arrivals they will recruit next summer. Well, considering that De Bruyne has now returned from his injury, it seems Pep will be more serious about reducing the point difference in his Domestic League. also, City will try to take over the top of the standings again. Talking about the last 16 of the Champions League, although in football it is unique and cannot be predicted with certainty. but in any case, City has a fairly large probability of qualifying for the next round.