Although, PSG once beat the incredible Manchester City side of 2021 in the group stage 2 - 0, yeah at that time Mbappe, Messi and Neymar were all playing for PSG then, I think Messi even scored in that game, I really can't totally remember though. Although, City beat them 2 - 1 in the return leg. But like you said, PSG didn't dominate the match, it was Manchester that dominated even though they lost 2 - 0 in that very game. In my opinion, PSG has the tendency of going far in this season, if I'm not mistaken they might actually eliminate Real Madrid that's if both of them gets to meet in the SF.
Even with the squad quality PSG had at that time they were not playing as good as this current PSG team under Luis Enrique are playing. I also believe that if this current team are to play Real Madrid in the semi finals of the Champions League there is a huge possibility that they can win the round though Real Madrid are also very good in the Champions League so it will be a good and entertaining game to watch.
Yeah you are right when PSG had good number of world best players they where unable to perform the way they are performing now I think there performance now is better than there performance then, they are playing very well and are very much ready to lift the champions League title this season but it won't be that easy for them but is possible if they should put in there best, if they succeed in lifting the champions League title this season I believe kylian mbappe will really feel bad for living the team because one of the major reasons he lift PSG was because PSG was unable to lift the champions League title and he really wanted to lift that trophy, he tried his best to make sure they succeed in lifting the champions League title when he was in PSG but it didn't work, so he decided to leave with the hope that he will lift the champions League and get to carry the ballon d'Or in real Madrid.
Well if PSG and real Madrid should meet in this seasons champions League it will be an interesting match kylian mbappe will play his best to make sure they win PSG even if is his former team, the match will be a difficult match and I really can't predict who may when if they should meet.