In my opinion, the French League is one of the weakest leagues among the European leagues. The quality of football in this league is not very high, the players and teams are below the Champions League level.
For a few seasons PSG performed well, among the other teams there was no team that had a chance of winning the title, perhaps they have not been very successful in the last 20 years. The 3rd and 4th teams in the Champions League will be easy opponents for other teams

If you look further, why this league is not as competitive as other leagues is because the teams there do not have the financial capacity like PSG so they cannot buy players to compete. The level of Ligue 1 is actually far behind several other leagues and PSG's dominance cannot be separated from their financial capabilities so that the quality of the players they have is above the average of the players owned by other teams there.
Football now requires the involvement of sufficient money and that is very important because they will look strong when they are able to buy the players they need. The strength of other teams only relies on limited players and in fact it will be quite difficult for them to break PSG's dominance.