Honestly I have seen Messi passing to Mbappe for a score a few times this year already and it looks like it is getting more common. I am not sure how many assists Messi has to Mbappe, but if someone calculated I am sure it is over 5 already, and that is a huge deal because you do not see that kind of numbers that easily. Which if you ask me is a proof that they are getting along very well.
We also know that Neymar and Messi go along very well too, one question remaining seems to be Neymar vs Mbappe, but if Messi could bring that together or at least they could be professional about it, then this team seems to be quite impossible to stop by any team in the world, they are that good when they play 100%.
almost all the goals scored by Mbappe are assists from messi, at least in 6 PSG matches Messi has contributed to providing 6 assists. messi is a very clever player in seeing gaps and providing feedback to his teammates. Thus, I think it's very clear that Galtier has put Mbappe as a Target Man.
In six matches, Messi's performance is the most stable when compared to Neymar, let alone Mbappe. this season, messi is playing so well, he has no serious problems with almost all his team-mates.
The problem that always raises issues around the PSG squad is none other than Neymar and Mbappe. these two stars always have disputes and feuds that are always raised by the sports media as a hot issue.
Well, again about the privileges that Mbappe has, is the trigger for all the existing disputes.
as you said, if Neymar and Mbappe can lower their egos and prioritize the interests of the club, it is not impossible that they can win the champions league trophy for the first time.