Even before Dortmund sold Haaland it was a weak team (compared to the top ones), now it is obviously even weaker and I would not be surprised if they are moved from second place to third and maybe even fourth in the upcoming season. As for Bayern, they will not have any problems in the domestic championship, as for the Champions League, randomness is of great importance there, but they will definitely be in the group of favorites.
They are not weak but just not strong enough to win Bundesliga. It is from Dortmund, not too strong enough and the over domination of Bayern in Bundesliga. Getting the runner up position will still be a challenge for Dortmund but they can do it. Other clubs in Bundesliga are not actually stronger than Dortmund. So Dortmund will still have chance and be able to get it. It is not easy for them but they can get it.
Of course they are weak. They lost every tournament last year and in most of them they were eliminated not by Bayern at all, but by other much weaker teams. The Champions League, then the Europa League, the German Cup - they failed everywhere. Now that Haaland is gone, it's hard to imagine that they've gotten stronger, right? And this means that in the upcoming season their achievements will hardly be better.
Honestly I don't expect much from Borussia Dortmund if they still behave like this (only making money from selling players). Even if there is a statement from them that they want achievement, I will laugh at that. What they need to do now is to improve the team first and not to be too greedy with profits.