When it comes to Bundesliga it is very possible that Bayern Munich can win because they are the defending champions and they might still have that heat in them but we should also not forget the fact there other clubs and Leverkusen is doing some improvement and that might be very challenging because Dortmund seems to been doing well to because they won there last match.
I wouldn't say Leverkusen is making improvements. They lost a top coach and took on Ten-Hag, who is a bit of a risky move. They sold some of their top players: Wirtz, Frimpong and Kossounou, they acquired some replacement players with decent potential, namely Quansah (from Liverpool) and Tillman (from PSV), but they're not rated as high as the leavers. So overall, at least on paper, Leverkusen is not as strong as it was last year or the year before.
I have a feeling that Borussia Dortmund might finish above Leverkusen this season, but I don't think either of them would be able to snatch the title from Bayern.