As long as Bayern Munich can work well as a team, there will be a chance to win against Manchester City. Some of the teams that have beaten Manchester City use good teamwork and always guard their attacking players like Erling Haaland, so it's not easy to get the ball and there's no chance for Manchester City to score.
You don't seem to watch the game from Manchester City, they are quite consistent in the games they play, it's quite difficult for a team to break Haaland's movement, he is quite agile when he has the ball.
I think Bayern Munich will have difficulty scoring many goals against Manchester City because Manchester City has a pretty strong defense.
Even though Bayern Munich is the host in the second leg, their opponent is not an easy team to beat. Manchester city will not give up just like that, it will certainly be able to provide a balanced resistance in the second leg.
Manchester city has always failed in previous seasons in the champions league. They will try their best in this season because their squad is quite strong in this season.
If Bayern makes a comeback it would be even more impressive than the comeback Liverpool once had against Barcelona. Liverpool wasn't playing bad at the time, but the first leg went so wrong for them. Tuchel has now repeatedly said that they played good against Manchester City for 70 minutes, but I disagree. It was ok, but it wasn't good. It's easy to say that it was good for so long, but Bayern never had the upper hand. In my opinion it was quite even at best in some phases of the game.
Now you have the massive disadvantage of three goals and Manchester City can focus on control and counter attacks, slow the game down as they don't need to score. There are also so many experiments and Bayern lacks an outstanding offender. Letting Gnabry play that position also wasn't very good. They still have to try, but it's also as if some of the Bayern players are not in good shape either. Sacking Nagelsmann and signing Tuchel changed 0.0%. Nagelsmann must be amused by now and Tuchel is about to lose it all. They are lucky that Dortmund constantly sucks as well or they would even lose the Bundesliga title as well.