I am not underestimating Arsenal but Arsenal won't do very well in Champions League but this team will definitely do well in Premier League. Last season we saw Arsenal came very close to winning Premier League but in the end most of the players were injured so they won the Premier League title. As you said Arsenal can't do well in the Champions League but will be a stumbling block for the favourites. In the important matches of the favorite teams, Arsenal will be seen as their obstacle. It is very interesting to see if the new teams do well in the Champions League, we hope that Arsenal will do well in the Champions League.
Arsenal are a different team with Arteta, especially in the last two seasons. Arteta has made Arsenal a very competitive team even though they have a relatively younger squad, but of course their winning mentality hasn't really taken shape. Arsenal can compete with any team in the Champions League, but I'm sure they won't win the title next season.
I also believe that Arsenal will have a good form in the Premier League next season, but again I have not been able to convince myself about Arsenal's possibility of winning the title. So I don't underestimate Arsenal either, but they won't win the title if this team doesn't have a good winning mentality next season.