These teams can certainly do well in European competitions, because they are not exactly teams that play little football, on the contrary they enjoy themselves and make others have fun, so I am confident that they can have a great run, even if there are some things to fix, but with time you will see that they will do it, they just have to understand from the first matches what is wrong.
The Champions League always has a unique story every season, as teams from various leagues gather here to compete, relying on their established skills. And in this regard, I always have more faith in the teams in the Premier League, La Liga, and Serie A than in other leagues, even though last season PSG surprised everyone by winning their first Champions League. But this season, I'm not even sure PSG will win another trophy in the Champions League, even though PSG still has the ability to fight like last season.
Yes it makes sense as you say. PSG will certainly struggle to defend their title this season especially since many other big teams have made improvements and brought in players to strengthen their squads. Furthermore if we look at the history of UCL champions, only Real Madrid has won back to back titles, and no other team has. Even when Man City won the UCL their performance was impressive making it difficult to beat them that season but they were eliminated in the next season. This could also happen to PSG this season.
Interestingly the EPL has sent the most representatives to the UCL this season compared to other leagues. They sent six teams to the UCL this season. I can't wait to see if one of the EPL teams can reach the final or even win the UCL this season or if they all fall.