Lewandowski scored 19 goals in 35 matches last year, but this season he has reached 14 goals. This number of goals is quite good. Considering that there are still 26 matches left in the season, if he plays in 26 matches, he can probably pass the 30 goal threshold. However, you may be wrong about Mbappé. Mbappé is a very talented player and may explode later. He has only scored six goals so far, but he is a player who even has the potential to score a hattrick. If he scores a few hattricks in a few matches, he can be at the top of the scorers list.
Lewandowski's performance is much better than last season and the goal statistics he has scored are also quite good this season so there is a big possibility that he will be one of the top scorer candidates at the end of the season. Hansi Flick is able to develop the best potential that Lewandowski has so that so far his productivity in scoring goals continues to improve and the average victory obtained by Barcelona is also quite promising this season.
Mbappe has not been as prolific as he once was and may need to adapt better to get the chances to continue scoring goals. He is talented and has the skills to score goals but he is not at his best at the moment.