Because considering the next match in the Champions League for Manchester City will take place at the end of January, of course it is very appropriate for Manchester City to resolve its weaknesses before that match takes place. And this is certainly very reasonable because if in the next two matches Manchester City cannot win, clearly there is no hope for Manchester City to qualify for the playoffs in the Champions League this season. In addition, if the team's weaknesses are better known by Pep Guardiola, of course the wise steps that will be taken by the team can also be quite easy without having to think about other less important things.
There is still plenty of time for both teams to prepare for the match and maybe later there will be some changes that will be made by Pep Guardiola to get more satisfying results in the match. If you look at the current table list, Man City is much more likely to qualify for the next round while PSG is in a disadvantageous position because they could lose the opportunity to qualify for the next round through the playoffs.
PSG also need a win in this match and their chances of qualifying for the next round are very small if they lose, so they will definitely try to do something better, especially since the match will take place at their home ground so their chances may be a little bigger.