Looking at the four teams representing Ligue 1 that qualified for next season UCL, only PSG can compete. Lille, Lens, and Lyon seem to have a difficult time competing because their squads are not on par with PSG, as are their financial resources. These clubs often sell good players whenever they have a chance, which is why PSG has always dominated Ligue 1. Unfortunately, this season, Monaco failed to qualify for next season's UCL. Usually, Monaco is a team that frequently competes in the UCL alongside PSG and Monaco often surprises the big teams in the UCL.
What happened in Ligue 1 is similar to what happened in the Bundesliga, as both leagues are dominated by one club PSG and Bayern Munich. Although many consider these two leagues to be the Farmers' League, these two teams are truly strong in the UCL, especially when facing teams from competitive leagues like the EPL and La Liga. PSG and Munich often perform exceptionally well, despite being in the Farmers' League. Perhaps it's true that PSG easier competition in Ligue 1 allows them to focus more on the UCL, allowing them to focus and perform at their best.
competing in the champions league is a very difficult thing for many teams and for this reason for those that have problems and also have little budget there are smaller competitions, but this does not mean they are made up of teams that are not strong, in fact i think there are great teams there too.