It might be that Francis Ngannou has tasted money in boxing, jumped in MMA for a fight against Renan Ferreira, understood that winning in MMA is easier for him, but he needs to have several fights to get paid the same as in boxing, and he decided to search for a rematch opportunity. Obviously a fight against Tyson Fury brought him more money and he felt that he is able to win it, compared to a fight against Anthony Joshua, so he would be calling and trying to fight Fury, especially when Fury should be demotivated after two losses.