but of course if you look at PSG, they really worked hard to win the trophy last season and of course many did not expect that PSG would win the Champions League. yes of course we'll see what happens in the coming season whether it's the same or not as before, but PSG should be able to easily win consistently in the upcoming Champions League matches if you look at their status who just lifted the UCL trophy. in my opinion sometimes in the UCL and domestic leagues there are always differences, but yes most of the time as you said of course the domestic league has more influence in the Champions League.
They began the last season in Champions League very bad but with time, they got good improvement and at the end they won it impressively by beating Inter Milan in the final match with a landslide result. Through their title in Champions League, they shown that they not only won it but actually built up a very young and competitive team that can be able to win more titles in future.
Winning Champions League title is not easy but PSG already won it after fighting for it in many years. They are able to play well in Champions League again but surely defending this title is never easy and only Real Madrid succeeded in history. PSG will try to do this and it's not because they want to be a second champion can do this, but there is no champion that does not want to defend their crown.