They are currently considered the favorites to win next year's Champions League by many betting sites. Paris Saint-Germain is a fantastic team and could be in a very good position next year. They may have lost the World Cup final against Chelsea, but that doesn't make them weak or ineffective. They will undoubtedly be the sole favorites to win next year's French league, and they will also be fighting for and potentially winning the Champions League. Of course, a Super Cup match awaits them, and they'll likely start the season with a trophy.
Even in the club world cup, they were considered the favourite by many casinos, when they got to the finals it even became worse as they placed some low odds on them in a way that felt like they were some kind of so sure PSG were going to win but in the end happened differently. For the French League, it is even more realistic they will be the winners but defending the champions is going to be some tough thing to do such that they may not survive it in the end. PSG does not have that consistency the likes of Madrid and Manchester City had that can get them to sustain their form to defending the trophy, the casino are just making them favourites based on their taughts but you still have the freedom to choose otherwise.