I think now that Arsenal knows they are going to play against Bayern Munich, you are worried because of the past games because now there is a chance for Bayern Munich to score five goals again against Arsenal. Except for the recent fiend match they had in ~5 years ago in which Arsenal won the game with a 2-1 result. In the other games they had, Bayern Munich won the game with a 5-1 result, and scoring five goals is not something normal at all.
Now Arsenal is not in a bad situation Bayern Munich is under pressure because of losing the Bundesliga title and they have to beat Arsenal, I'm waiting to see how Bayern Munich and Tuchel can perform against Arsenal.
Yeah both teams are in different situations this season we can't compare their performance based on last season's matches and each team has its own advantages, here in the first leg Arsenal are very favorites to win then in the second leg of course Bayern Munich are the favourites well as I said before the goal difference will determine who will go to the next stage. One thing I note is that Arsenal is on fire in the Premier League while Bayern Munchen are not doing much better due to some recent bad results..
Actually, Bayern Munich are still in the same performance as last season, because if we compare them in terms of points, actually their points tally is not much different, it's just that what makes them look like they are declining is because Leverkusen has performed so extraordinary this season that it has created a big gap. It seems as if Bayern Munich is performing badly, even though it's actually not.
Arsenal are better than last season, I agree, because they can survive this far and I can't remember the last time they were in the quarter-finals like this. Even in the Premier League, they can still show very tight competition, they are even at the top of the standings even though in terms of points there is actually no gap between them. However, if compared with last season, they couldn't even survive when they needed a good performance to be able to compete, but they couldn't do it until the end. But this season they look better prepared than before, so their chances are also bigger in my opinion.