They literally just did it for money. Too lazy to make a new story so they’re destroying this one instead
Honestly if you look closely I don’t think it was sudden from the author. The author was already testing the water in the 4th season with that red hair guy getting chained up and raped then in the epilogue there was 2 scenes where Taesung forced himself on Haebom at his dads house and at the end of the story. The author (fuck her) probably saw how people still supported the story + the insane fame “Jinx” got and decided to milk the story. (Fuck her again!)
Did the author suddenly adopt a masochistic kink? How do you just roll over to an old and basically complete story and take a piss all over it? Did they lose a bet or their mind? This entire alternate plot line is complete rubbish, they aren't being edgy or whatever their goal is, what a huge fail!