In Ligue 1, what you said is true, other clubs are too weak and barely can have good seasons to challenge PSG and beat this giant club. PSG many times had their bad matches but they still completed those seasons with titles because other clubs are too weak to take advantage of PSG's poor performances. In domestic league, PSG easily won titles but it becomes their weaknesses when they play in Champions League. Being familiar with lower quality of matches in Ligue 1 and weak opponents there, they don't have enough quality, carefulness and preparations for tough matches in Champions League.
PSG fought really hard each season to become the UCL Champs but it seems their hardwork is not good enough and I guess it's time for them to upgrade their level of football. PSG are not serious in their league matches, they have top priority, and it's lifting the UEFA Champions League trophy, this is the exact scenario that PSG president, Nasser Al-Khelaifi have been working on, it doesn't last long to watch PSG getting eliminated, however this is new season and It comes with lots of surprises. Other clubs don't possess the big force to drive to becoming threats for Paris Saint-Germain.
I wouldn't be surprised if PSG has almost no equal opponents in League 1, even in the last few seasons there has been no other club that can displace this club from first place and for me it is clear that PSG is still very strong when it has a star player like Mbappe. and do we think that if Mbappe leaves PSG will still be able to win the league 1 title?
No, I would doubt PSG if one day they lost Mbappe, this club performance would definitely decline and I would also see from the other side that without Mbappe presence this club would be a little weak.
I admit that the PSG president always prioritizes the champions league title, but for me it would be impossible if he didn't give the coach the opportunity to find the right strategy and on the one hand, losing a mainstay player would definitely affect the strength of competing in the champions league.
Unless the PSG president is willing to look for a reliable coach who has a lot of experience, then keep him for the next few seasons and I am sure that in this way PSG will have the opportunity to wins the champions league title.
It's actually a little sad to see PSG's efforts to bring the club to win the Champions League title, spending a lot of money when bringing in Messi and Neymar, but it's all the same PSG was only able to win the title in League 1 without having a title to be proud of.