if you look in the artist credit, it's still the same artist. I think the art style changed because the artist had to produce the chapters at a rapid pace due to the publishing schedules
So he saw that huimin was so traumatized by what he did he made up an entire new world in his mind to cope w the trauma and after seeing all that he just goes "yeah imma do the same thing again"
Bruh why the siblings in these manhwas always gotta be freaky like why cant we have ONE time where its just a brothely love dawg whys it gotta be weird
The 5 different angle panty shots are CRUCIAL to the plot guys