Several of the top teams in Ligue 1 this season have experienced a decline, Marseille experienced a decline after Igor Tudor left. Lyon was even worse, they were in the red zone and finally were able to be in a safer zone. Nice was in the top four of the standings, but in the end they dropped by themselves because this team actually didn't have much depth.
Now, Brest is in 2nd place in the standings. however, it is only a matter of time to be overtaken by Monaco. after all, these two teams still have one meeting left. I'm still quite optimistic that Manaco will be able to finish in 2nd place by the end of this season.

As for Lille, I'm not too sure. But at least they still have a chance to finish in the top four of Ligue 1, even though Lillie is currently in 3rd place. However, if Monaco wins the match against Rennes, the position occupied by Lille will be taken over again. Maybe this week, Brest's position will not be marginalized if we look at their opponent, Metz. but there is no guarantee that Brest can win the match. In the following week, Brest has a match against Lyon and after that against Monaco. so, it is not an easy job for Brest to maintain its ranking until the end of the season.