The Other Side of Night

i didn't read the synopsis or tags so if I knew beforehand that the sci-fi part IS the plot twist i wouldn't even read it. i love sci-fi and fantasy and other genres but I absolutely HATE it when they become a plot twist in thrillers bc its not a thriller anymore?? i was so invested in the story and had so many theories and the second the reveal came i literally almost dnfed the book bc what's the point in finishing