When a club is overhauling its squad, it is difficult to measure its true strength. It was coming with an unfamiliar face that had not yet faced Bayern, and how can we judge whether Arsenal won or lost against Bayern? I believe that if the reason is clear, Arsenal may be on par with Bayern Munich right now but anything can happen even arsenal can also own bayern too.
There have been no significant improvements to the bayern. I believe that the previous-used historical data is no longer reliable because both clubs will be performing with different squads. Arsenal has been rebuilding its squad, and that is it. Even if Barcelona faced City with a different squad, historical data would not be reliable to use there. You do have different composition and you will have also different gameplay. that's it

Arsenal is the favorite to win the game, given that the first game will be away. This also forces Bayern Munich to work even harder to prevent Arsenal from winning the game soon. The outcome of these matches is also difficult to predict.
Just because Arsenal is playing Bayern Munich, we can use historical head-to-head data to predict which team will win the game. Same data, same call.
I can't really judge whether bayern will dominate arsenal like the previous matches since all of things have changed on arsenal after it has a coach that can be even more structured than before which was pep,