Therefore, his new work acquires a certain scientific interest in my eyes. This should be a new hit from a successful author, but Aka decided to repeat the move of the Game of Thrones showrunners and just ruined his own life out of the blue. So now a lot of people will be watching how (potentially) quickly this will fail, not so much because of the mediocre premise, but because of the terrible planning and work morale of Aka himself. Plus, obviously the editors will now give him much less creative and simply working freedom, because they will know that Aka is a good author who does not justify much credit by immediately destroying things when he is given freedom. In general, the dude himself ruined his triumph and now his not the best work will be under increased attention and control.
This is purely my speculation, but what if this situation is similar to the original Bleach one? I mean, when Shonen Jump just got tired of seeing ratings drop and fans complaining and they just demanded that Kubo end things in 4-5 chapters right in the middle of a drawn out arc. Keeping Kaguya's popularity and Bullet's situation in mind, what if it was the everyday elements that made Oshi no Ko last this long, while trying to turn it into an edgy tragedy simply killed the editors' enthusiasm? Mengo may also have played a role in this, given that many elements seemed to be taken from her collection of one-shots and her attempts to rewrite it for a wider audience may also have been part of the problem.