Despite Barcelona's dismal record against Bayern, I'm still very wary about their chances this season. However, I hope they don't approach the game with a revenge mindset as that could lead to more losing matches. If they are focusing on the game itself, rather than proving a point, we might see improvement. Hansi Flick's guidance could be the boost they need. Nevertheless, it's just a game, and we can't put too much hope into it, but I'm eager to see how they'll perform this season
If they eventually have the upper hand at the beginning of the game and they have the chance to put in more goals before the time runs out then they might want to consider taking a revenge game on Bayern , so far they can maintain their position then going for it shouldn't be bad actually.
However, I don't think Hansi Flick will want a revenge game though he might want as many as possible goals but taking it to a revenge plan... he absolutely won't do that even if they have the chance to proof that

and that's if its possible in the first place, Barcelona has some serious game ahead apart from UCL so securing the win might just be their target.
Hansi Flick main focus at the moment is of course trying to stabilize his team, especially since there are still weaknesses that are seen in their defense at the moment, the impressive performance so far they have managed to show and of course the match against Bayern Munich in the Champions League will be a very crucial match for them, in my opinion the revenge option is indeed inevitable will color the match, Especially if we remember Munich 8-2 victory over Barcelona which was indeed Munich coached by Hansi Flick at that time, the match will be an opportunity for Barcelona to break their negative trend over Munich so far, that the match will be a difficult match to predict because of the quality and strength of the team which is quite balanced, So indeed the factor of the coach's ability to manage and formulate game strategies in the match will be a factor that will greatly determine the victory of one of the two teams later.