Maintaining top form every season will certainly be difficult, especially as other teams have made significant improvements by signing new players, and their strategies will undoubtedly differ from the previous season.
So PSG journey in the UCL next season won't be as smooth as last season. After winning the UCL last season, their performance has declined, not improved. This was evident in the CWC competition, and most recently, they struggled to beat Tottenham. PSG's game against Tottenham was very readable, which led to them conceding easily, although Enrique's brilliant strategy ultimately led to a comeback. But overall, their game is already easy to read. Even against Tottenham who weren't the favorites in the UCL they were overwhelmed let alone in the UCL competition which will be filled with strong teams like Real Madrid, Barcelona, Munich, and Liverpool.
You're not far from the truth, of recent psg cannot recreate their exploit of last season in this present season that is about to start, looking at their performance in recent games and how they have now been struggling unlike before I don't see them as that team that teams were afraid of. If you watch the tottenham you will notice that psg could not open up spaces in the tottenham defence, this is something that they normally do with ease last season even if they are against big teams. If psg did this against a team like barca I'm very sure they would have lived to regret it