Only Real Madrid have been able to win the Champions League back to back. Apart from them no other club has done it. This is why I don't think that PSG can defend the title because they cannot be in the same form like last season. Many clubs have improved their performance by by additional players to strengthen the team. I believe that PSG will find it difficult to win some big teams that they defeated last season.
I would have loved to see a different club entirely winning the title this season.
Last year, PSG also had a difficult start to the season, and if you remember, they played very poorly in the Champions League, and at one point there was a danger they wouldn't even make the top 24. That is, they could have left the tournament after the group stage. But then, when it mattered most, they showed strength and dominated; for many years, no one had won the Champions League in such a style. Overall, it is unknown whether this could happen again; many teams have strengthened, and it is still too early to say.