It is still very early to talk about the bonding among the PSG players when we know what happened between Mbappe, Messi, Ramos and Naymer when they had the opportunity of playing together, PSG were seen as the team that would have won the champions league competition with the squad they had then but they were playing more of individual football because of the lack of bond in the team but now that Mbappe and the rest of the names are out of the team and the club now has a new coach and less big names, the coach should work on the performance of the team as well as the relationship among his players because I can't see that yet even though they have had an excellent performance in the beginning of the season so far.
PSG is playing good football and they still have what it takes to win the domestic league even without having big names in the team but the coach should focus the performance of his players on winning the Champions League this season because that's what the team needs right now since they are sure of winning the Ligue1.
They shouldn't have really expect those four to have that kind of great relationship though. Ramos and Mbappe are two players who one played for Madrid many years with Ronaldo, and the other can't wait to join Madrid soon following his idol Ronaldo, and Ramos was a little old too, and that meant those were the franco side, whereas the other two were Barcelona friends who played together and won together. So that four did not had the chemistry build to last, it was obvious it wouldn't work.
Even without any of that, getting three players who are that old, and injury prone as well, means that Mbappe was left so many times all alone. I think it looks like we are seeing them do better without any of them right now, they have no issues in the team.