Messi, Neymar and Mbappe all are still continuing in the World Cup which must be worrying news for PSG. Because even if one this great trio gets a serious injury then they might have a really big problem against Bayern Munich. PSG have got a very tough draw in last 16 round already. I assume they were hoping to face a weaker team. Now it is more important for them to keep their best players healthy.
Especially Neymar is very injury-prone. He already got an injury too as you know but he is good now. If he gets another one then it might be more serious. Because we are in the later stages of the World Cup and teams would try to defend their opponents harder then before.
It should be noted that the match in the Champions League is still a long time away. Their match will be held in February, which means that there are still a few months left from now, so why worry about something far more than that they are still in good condition, although some news say that Mbappe is having a little problem but it was only a small matter as the injury was not serious.