Champions League is definitely tougher than La Liga. Because almost every team in the Champions League is very strong. So continuing the winning streak in the Champions League is not an easy task. Barcelona was defeated in the first match of the Champions League. But in the second match we saw a great comeback from Barcelona. We saw Barcelona win by a huge margin of 5-0 against Young Boys.
On the other hand, we saw the Bayern Munich team win by a big margin in the opening matches of this season. But in the last three matches we have seen poor performances from Munich. Munich conceded 5 goals and scored 4 in the last three matches. Munich's overall performance is now weak. So it will be very difficult for Munich to get 3 points against Barcelona. I'd say both Munich and Barcelona have a 50-50 chance of winning.
Speaking of H2H, it is clear that Bayern Munich outperforms but now it might be a little different where Flick could overthrow Bayern Munich at home, although it is not certain, let's just say that like a wild prediction, the 50:50 chance is correct.
Even for the bettors may still believe they will bet on Barcelona despite having a bad record when meeting Bayern Munich. Instead here Barcelona have their own motivation where they can win over Bayern Munich.
Not going to conclude now, maybe the odds I think the most is that both teams score this score is still very likely to win the odds.