So honest question here...what next?
In a few dozen chapters, we've gone from the first glimmer of potential in his power, to killing the calamity dragon as powerful as any ever known in legend. Where do we go from here? Where could we go from here? If we are escalating the MC's power, about all that is left is to kill gods, and we don't know if gods even exist.
There's nowhere for the writer to go. All I can think is that he was given some courtesy warning that the axe was falling in about six issues, so he decided to speedrun to the final boss so that he could be axed with style.