Brest is actually a team competing in the middle of the table, but last season they were surprisingly able to show a very good performance so that they were able to be in 3rd position and also go to the Champions League to represent Ligue 1 with Paris Saint Germain and Monaco. It was an achievement for them because they were able to show something good like that. This season they started the league with a less than good performance so that they have already felt 2 defeats. I personally am not too surprised if Brest declines at this time, because they have just been in the top board and maybe they are not used to the pressure and expectations that come to them. There is still time for them to rise and return to showing performance like last season.
What happened with Brest last season is the same thing that Lens felt in the previous 2 seasons where indeed they are a club that is actually always in the middle of the table but when there is good momentum they sometimes become a surprise club. But something like that can't keep happening every season because it only happens in some unexpected seasons. So when last season they played and had a good performance, it would not be surprising if the next season they would be a little troubled to undergo the season.
I actually don't expect too much from Brest but indeed when they are now in the Champions League then the situation is clearly different because after all this has become a big competition and representatives of each major competition in Europe are a reflection of the league itself so they have to work hard to show that ligue 1 is not bad for a big competition and not just use PSG as a shield for now.