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.
In my opinion, now is the right time for big clubs to buy him, because a player like Haalaand will certainly be in demand by many clubs and of course it will be very difficult to get Haalaand in the summer transfer market, the competition to get Haaland is certainly very tight in summer transfer and of course for some the team will be very difficult in this case, but I think it's not wrong to pay a lot of money for a player like haaland now, although maybe the club can't use him temporarily in european competition, but to secure the signature of haaland of course it's luck for the club in my opinion.