If Haaland leaves for another club already in this transfer window, it will look like a disaster for Borussia Dortmund, because the club is not ready for this and the team will lose a player who made a significant contribution to scoring points in the Bundesliga. I strongly doubt that the transfer will take place now, because it seems that the point of the contract on the amount of the buyout, which everyone is talking about, should come into force in the summer. Also, it seems that all the rumors about potential buyers speak about the willingness to pay this amount. Although I think that the amount will still be higher than the potential 75 million euros.
Considering that Haaland has already played for Borussia in the Champions League this season, he will not be able to help his new club even if he is bought in this transfer window, so I think there is no point in buying Haaland now. This will only lead to a large overpayment (both in the player's price and in the payment of his salary). Although it may be clubs like Barcelona or Newcastle would be happy to use him to improve their affairs in the domestic championships.
It's important for Haaland to be quick at halftime. Yes, maybe Haaland will not be able to play in European matches when he is transferred, but you will add Haaland to your squad before other teams. He played a successful game again in Dortmund this year. The transfer season has arrived and in 2022 Dortmund will want to earn more than his transfer fee. That's why I think he can transfer with a big club in the interim transfer period, that is, in the coming days.