Bayern Munich's defeat proved that Kompanty is very dependent on striker Harry Kane. When Kane was absent, Bayern Munich had difficulty breaking down the opponent's defense, in this case Mainz's defense, to score goals. This can also be seen from the actual game statistics. Bayern Munich dominated the match with 69% ball possession and released 13 shots, but they only managed to make 1 shot on target and it was ineffective. Without Harry Kane, Bayern Munich could not win the match and this was their first defeat after 13 matches without defeat.
On the other hand, in this match Mainz also appeared very effective and clinical. It was seen that they tried 8 attempts at kicks and 4 of them were on target, even though they only got 31% ball possession but they played very effectively. In the end, Mainz gave Bayern Munich their first defeat in the Bundesliga, this defeat not only made Kompanty have to learn from his mistakes but he also had to be able to play the role of all players without having to rely on just one player. So if there is an injured player he can utilize the potential of other players.
I don't think it was only because of Kane absence that Bayern Munich lost their match against Mainz. Bayern Munich played with a lot of injuries, they were without some key first team players like Manuel Neur, Alphonso Davies. Mainz played very well, they were able to take advantage of Bayern Munich’s weak defense. It was a step up from a disappointing outing against Wolfsburg in their previous match.
Bayarn Munich were unbeaten in the Bundesliga until the 13th match and thought that they might do better this season than last season but they could not maintain their consistent performance till the 14th match. They dropped points in 14th match against Mainz and losing this match is not good for them as another team in the league is not far behind them. If Bayern Munich perform like this in their next match, if Leverkusen get full points in their next match, they will be back level with Bayern Munich on points. I can partly blame the absence of Harry Kane as the reason for Bayarn Munich's defeat against Mainz because if this striker was there he would have scored and if he had scored the team would have won.