I am only speaking on Korean to Western published games, as those are the ones I have worked for in the past, developers have a product already so the fixes are expected of them and no extra money is given for them as they are part of the weekly/bi weekly patches for such serviced games.
I fully expect it to be the same case with Neowiz and Bandai deal as its the norm for Korean developers to keep the rights and direction of a game under control, after all that is why they are self publishing it on PC and didn't give Bandai the chance to even discuss beyond console publishing rights.