Kane is a very influential player in the front line and has contributed greatly to the team so far, but that doesn't mean Bayern Munich's dependence on Kane is very high and the defeat to Mainz last weekend was not solely due to Kane's absence.
But for now I think Kane can make a significant impact on Munich's performance. He is the top scorer in the Bundesliga which means if Kane was not injured and played in that match I think Munich would have had a different result. At least the match would have ended in a draw. I'm not saying Kane is Munich's only hope but I think Munich dominated Mainz in that match but unfortunately Munich couldn't create many chances. They made 13 shots but only 1 shot on target. But in the end a win is a win and I respect Mainz and I think they deserved the win and became the first team to beat Munich this season.
This is just speculation because at the same time Kane can't play, the view would change if Kane was in the squad and could play in the match.
Judging from the way they attacked, they actually lost their creativity after Mainz was able to implement a defense that was difficult to penetrate. So this is not entirely due to Kane's absence in this match, but rather there is a strategy that is not working. There are several factors that influence, it could be because Mainz was successful with their strategy or because Bayern Munich's strategy implementation in this match was not optimal so they found a dead end when attacking.