i don't think the problem is with Messi and Mbappe not playing well together, i've seen some good chemistry between them in a lot of matches, Messi got that killer pass and Mbappe got the speed, that's an amazing combination, midfield of PSG is weak in my opinion, they really need an upgrade there.
The problem is not that Messi or Mbappe are not playing well, every PSG player has responsibility for the consecutive defeats that PSG have had in the last two matches. PSG players didn't build good chemistry, they played very badly which made them lose 6 points at their base.
As a result of the last defeat that befell PSG at their headquarters, speculation about Messi departure has intensified. PSG fans always booed Messi for not being able to bring PSG through to the quarterfinals of the UCL. Defeats from Rennes and Lyon made Lens manage to close the distance with PSG, now Lens, who is in second place, is only six points away from PSG who are still in first place.
PSG must immediately get out of the slump to secure its position. It looks like Galtier time with PSG won't last long, due to the failure in the UCL and the bad results he continues to achieve in Ligue 1, making the coach chair held by Galtier shake even more.