They are still talented players of course but they are in a new environment and they need some time to adapt to playing together.
For example we saw this need in the match against Lorient. There was a big dominance but no goal as I said. But after this adaptation process ends I will be expecting to see a much better PSG. For now they aren't a very credible team to bet on. But this is my opinion of course.
Adaptation is necessary, but from some players who are really great and have the capability, it doesn't take them long to adapt and show their good performance. For example, Erling Haaland at Manchester City and Jude Bellingham at Real Madrid. September 4th we'll see Lyon match against PSG, Lyon is a pretty tough opponent even though they're currently at a slump at the start of the season, we'll see how PSG can see a good opportunity here or not.