When a team successfully wins the UCL, it does not mean that they will be able to do the same thing next season. PSG is not necessarily able to beat the same team that they beat last season. If this were Ligue 1, I am sure PSG would be champions again. They are too dominant in Ligue 1. But it is different with the UCL where the contestants are elite European teams who certainly have great motivation to win the UCL. Many teams have made player purchases to cover their shortcomings in the previous season. And this is a sign for PSG that they will not face a team with the same composition of players as before. I don't know if buying new players is the right decision for PSG because for this season I think their squad is perfect in all aspects.
With the new season, of course, the situation of each team will also be different. We can start to calculate it if the season has started. And we will see teams that have changed to be stronger and will compete in the Champions League.
There may also be teams that will be willing to not focus on their domestic league and choose to focus more on the Champions League. That shows how important it is for teams competing for the Champions League trophy. PSG will not be easy to win against again next season. Their competitors must also be getting stronger.