The results of past head-to-head matches should not be considered to select the favorite team this season. If we only consider the results of the head-to-head matches, then without a doubt the Bayern Munich team has to be considered as the favorite. I can't remember the last time I saw Barcelona win against Bayern Munich. Barcelona have lost their last 6 matches against Munich in the Champions League. Considering this aspect, the Bayern Munich team should be considered as the favorite in the next match as well.
Well, it looks like we can't use the previous head to head as a reference for the upcoming match. considering that the conditions of the two teams are in very different conditions from previous seasons. In several seasons, Barcelona has experienced defeats more often when facing Bayern because Barcelona has not been in good condition in the past few seasons. We can see that in the past few seasons Barcelona has always failed to go further in the UCL. but this season I think Barcelona is a little different. They are much better now than in previous seasons. So it is possible that Barcelona will succeed in getting full points in the match against Bayern.
The last time Barcelona won against Bayern was in 2015. And I think this season Barcelona has the potential to end the streak of defeats they have had in several seasons.