Inter Milan still hopes for the league title because their chance is still quite big, just a 1-point difference from Napoli. Meanwhile, PSG is very dominant in Ligue 1. They have secured the championship, so they are more relaxed in the league and can focus on the UCL Final. This could be a weak point for Inter. Although there is still almost a 3-week break, league matches could disrupt Inter's plans for the UCL Final. It could be physical condition, or it could be injuries. So, it is possible that Inter may not be at their best during the final.
Inter are still competing with Napoli in the hunt for the Scudetto, but PSG have already secured the Ligue 1 Trophy. This condition makes Inter players have to use all their abilities to win the title race, the risk of injury is very vulnerable at times like this and if that happens it will be very detrimental to them in the UCL final.
It is still difficult to predict who will win the UCL trophy this season because both teams have the same squad quality, but if Inter loses important players due to injury, then PSG has a great chance to win the Treble Winner.
Inter continues to fight to win the Italian league. That's why they can't play many matches with their reserve squad. Because if they take risks, they also have the risk of losing the Italian league. They have to play every match in the league with the best squad in the match with Napoli. They also have to prepare for the Champions League final. In France, Paris Saint-Germain's job is easier, they have already declared their championship. That's why they can easily put their reserve players on the field in League matches. That's why the French team's players are luckier in terms of rest.