It becomes boring for them because there is no tight competition, so they can easily get a title every season. But if the position is different with them getting tight pressure, then this league becomes more interesting and they will definitely be more enthusiastic to defend it.
This is very different, because in the Champions League they get a different situation. In the Champions League the situation is reversed, if in League 1 they are the team that should get pressure, in the Champions League they are the competitors who are expected to be able to give something good, because there are so many teams that are better than them.
This is the biggest disadvantage of the French League for Paris Saint-Germain. Because there is no team that can challenge them in the league. As such, Paris Saint-Germain is having a hard time in Europe. Because they are used to facing easy opponents in the French league and when they face a strong opponent, they struggle. Now their opponents are Liverpool and their job is very difficult because Liverpool is the favorite for this year's Champions League. This match will be a real test for Paris Saint-Germain.
Well that's the point, they are not used to high pressure, so when they get it in the Champions League then most likely they will not be fully prepared, because their mentality is not formed in domestic competitions. It's different from teams from the English League and La Liga for example, in the English League it is clearly the most competitive league. While in La Liga, although there may only be 3 teams that are able to compete at the top of the standings, the pressure they get is so high from those 3 teams, so that it makes their mentality even better trained.