Haven't really watched him play so don't want this to sound like a definitive judgement, but if you look at his stats on fbref he looses 2.5 challenges per game. That's obvioulsy in part because he takes so many (4 per game) but take Palinha for example who takes on 5 tackles per game but loses only 1.6 on average. Then you have the likes of Rodri and Rice who take on less challenges but win a much higher percentage of those than him. Add to that Ugartes short passing stats which, playing for a team as dominating domestically as PSG, are on par with Palinha playing for midtable/bottom-half Fulham in EPL. You don't even have to compare him to the elite of Rice and Rodri there, even Andrich, who plays the bulldog for Germany and Leverkusen has much better short passing success rate than Ugarte in that role of a bulldog whilsts losing a fifth the amount of challenges per game compared to Ugarte.
What I'm getting at is, whilsts it is nice to have this sort of bulldog on the team, if said bulldog loses his challenges or mishits his short and simple passes, more often than not it can open wide gaps for the opposition and add more negatives to the team than positives. All that being said, he is still young, especially for a position where experience is very important in regards to his possible weaknesses (decision making) and others who have watched him play might put those numbers in perspective. Just wanted to add some data to the discussion.