You are right that one of Kane obstacles with Bayern Munich in winning the Bundesliga title is Xabi protege and of course Leverkusen also cannot easily allow Bayern Munich to win the Bundesliga this season.
This is the biggest opportunity that Leverkusen and Xabi have so they will definitely try to fight for the achievement of becoming new champions.
What we know is that Kane moved from Tottenham to Munich hoping to get a taste of the title, but after looking at this season it looks like Leverkusen is a serious threat to Munich in the title race this season in the Bundesliga, Xabi is serious about maintaining his consistency in winning ways so he can win the title and breaking Munich's dominance in the Bundesliga, but on the one hand Munich will continue to chase Leverkusen.
At least if he fails in the Bundesliga, Kane also has the opportunity to taste the title in the UCL, but clearly that is very difficult because the competition in the UCL is very tight considering that Madrid and Manchester City are still a threat to them, if you look at it, there is still time for Munich to catch up. but they have to be consistent until the end of the season and wait for Leverkusen to really make a mistake.
Yes, Leverkusen is a real threat to Bayern Munich defending their title this season, including being a stumbling block for Kane who wants to experience the title in the Bundesliga. Usually we see Borussia Dortmund in Leverkusen's position and this season they can't do that. If Leverkusen is not there, then there is no serious competitor for Bayern Munich this season. I forget, but maybe this is something new for the Bundesliga where Bayern Munich is having difficulty with clubs other than Borussia Dortmund. Last season, it was clear that Borussia Dortmund was a club that was close to breaking Bayern Munich's dominance unless they failed in the deciding match.
This is an unpleasant thing for Kane, but this is a very pleasant thing for football fans, because they can see that there is a club that can make Bayern Munich have to work even harder to be able to defend the title.