PSG's job won't be easy in a tough group like Group F indeed. Newcastle, Dortmund and Milan are all challenging opponents for the current PSG. Because there isn't an impressive team play by PSG these days. They are expecting Mbappe to do most of the work. This can't help them be successful much in the Champions League.
This isn't the Ligue 1 in the end. PSG can find a way to maintain their title streak there but their job is very difficult in the Champions League. Mostly the team with the best team play win this title. We all saw what Manchester City did last season in the semi finals and finale even without Haaland's scoring or making an assist.
Actually, not all clubs in Group F will give Paris SG difficulties, but AC Milan will be the toughest challenger because looking at past history, Milan has had the experience of winning the Champions League trophy several times, while Paris SG has never won the title at all and for now even Milan performance is very strong and stable which makes us all doubt whether Paris SG can get past this challenger.
I really agree with you that in the Champions League a club cannot rely on just one player, but the Champions League is only for clubs that have very good cooperation between players, like last season when Haaland was unable to score in the final but other players also had to play a role. It is important to get goals to secure victory and this needs to be used as motivation for other clubs like Paris SGg if they want to get the Champions League trophy.