The change to Long Cheng's story just removed the perspective MFZ gained during the years he sequestered. Now MFZ seems like the father who abandoned his son and then comes back years later to start acting like a father instead of being the MFZ who comes back with the intention of helping out old friends who stuck by him using the new perspectives he gained during his reclusive life.
The altered ending of the arc is also changing the plot even further from the novel. I bet they're going to skip the volume that goes into some of MFZ's past and shows why the Seven Champion White Princes are a threat that can't just be killed as if they're fodder like every edge lord thinks.
And, for those still asking where to start in the novel from here, the answer hasn't changed: at the very least, start at the beginning of volume 2.