I don't think Bayern Munich's defeat against Dortmund in the Bundesliga can be used as a reference for the match against Dortmund because of the different motivations between the two teams.
While the match against Arsenal will be different, Bayern Munich has the possibility of being slightly better than what happened in the previous season in the meeting between the two and in terms of quality these two teams have almost equal strength so indeed the Bayern Munich vs Arsenal quarter-final match will be quite fierce and very interesting.
Indeed, that cannot be used as a reference, but at least we can see how Bayern Muncih was defeated in that match, even when they acted as hosts and were the team that was the favorite to win this match. With this result, Arsenal seemed to get a breath of fresh air over what was achieved by Bayern Munich. Indeed, this match is different, but Arsenal also definitely realizes what they have to do so that they can do the same thing as Borussia Dortmund.
On the other hand, Bayern Munich must immediately forget about this defeat, because if they don't forget it quickly then maybe it will affect their mentality. You also need to remember that this is the Champions League and mentality is really needed when in this competition.