Bayern is just trying their best to be the best team with the money they have and mane is their big hope to replace Lewandowski but talent like Lewa is hard to find. there is still hope for Bayern to be able to maintain their good performance, as long as they manage to get harry kane then their problem will be solved.
Players who have high skills and patience like Robert Lewandowski are very difficult to find, but if Bayern Munich prefers players who have a young age with good skills, maybe they will get it easily, because Robert Lewandowski is a player that is really wanted by many teams.
Lewandowski was a great player for Bayern Munich, the reason Bayern Munich sold Lewandowski out to Barcelona is because they know sadio Mane can cover up for the team if Lewandowski leaves the club , sadio Mane is doing well for Bayern Munich.
Sadio Mane and Lewandowski are two players with different qualities and experience. Lewandowski's contribution cannot be completely covered by Sadio Mane, additions are required to offset these contributions.Even though previously Sadio Mane was one of the best players in the EPL with Liverpool, competition in the EPL and the Bundesliga has a different level.
I'm not saying Sadio Mane's transfer was the wrong decision, but compare with Lewandowski's contribution, I don't think it's enough.