I think Arsenal is in the luckiest group because the other 3 teams are weaker than them. I still think about how they lost to Lens. Lens are in a bad situation in League 1, but we can also say that they are fully concentrating on the UCL. They are currently leaders in the group with 4 points from 2 matches.
Arsenal still often experience consistency problems, last season they had the chance to win the EPL, but in the second half of the season they often made mistakes, so the standings were taken over by Man. City. Lens, which is not performing well in the French league, might be used to focus on the UCL. At least they can put pressure on other teams to qualify for the knockout phase. The inconsistencies often experienced by Arsenal were successfully exploited by Lens to get points from the match. I believe this victory has given Lens confidence to accompany Arsenal as a team to qualify for the next phase.