Oda is tired of the manga. The Raid, and Wano itself, have been lame, Oda just put references to japanese mythology and think thats good.
The SH in the raid have no clear objective and just run aroud without knowing what to do. Mostly of the readers would love if Oda focus more on individual chapters of the SH fighting the Beast Pirates, but he keep putting focus on Wano characters that no one cares about.
And of all the problems, BM seems to be the biggest one for me. He dont know what to do with her, she should be a as dangerous as Kaido, but have become a character that everyone know will do nothing, but is too strong for someone to just defeat and take out of the plot, soo he keep creating this things to make her less of a threat and put her away from the main plot until late in the arc, as he know that if her and Kaido join and go full against Luffy and cia there's no way for the alliance to win.
Even with all this problems, i think at the end he want to make her betray Kaido and have a good use for her more late in the arc. Kaido and BM have been part of the Rocks, and this theme of betray and the idea that "all pirates alliances end in betray" have been show since Luffy alliance with Law. Pehaps more late in the arc BM will find Kaido road poneglyph and seeing a good opportunity, as Kaido will be weakend after fighting Luffy, she will try to take him out, and the fight between the two will be the thing that will weakend the Emperors enought for the Supernova to defeat them. The problem is, until this time came Oda dont know what to do with her.