I also think they can defend their championship in the French league, but when it comes to the Champions League, the probability may be lower. Because when you go to the eliminations outside of the group stage, every team can get surprising results. This year, the fight between Barcelona and Inter was the simplest example of this. While everyone expected Barcelona to win easily, Inter eliminated them. They made it to the final and played very badly against Paris Saint-Germain in the final. I don't know if Barcelona could have won the cup if they had made it to the final, but football is such a game, that's what I want to say.
Even if PSG wins the Champions League this season, it will be very difficult for PSG to retain this title next season. Some of the teams that we considered as favorites at the beginning of last season did not do well this season, but PSG won the Champions League title. Now, if Real Madrid, Manchester City and other strong teams return to the competition well next season, then it will be difficult for PSG to qualify for the semi-finals. I would like PSG to strengthen their team even more and recruit some important players to the club so that this French league team can compete well with Real Madrid and other teams if they perform well next season.
Only Real Madrid has won the Champions League back-to-back. PSG can also try to create another record for themselves next season by defending the title, but I don't that's possible because they would still be carried away with the excitement of being the defending champion and might lose focus on taking their matches seriously like they did this season.