To understand why Alexandra cursed a second ago, we must go back in time a couple of minutes, when she was still clashing with the Genesis Core of the Fritz elder.
The male elder from the Pleasure Palace was being blocked every time he tried to either kill on of the three girls that were fighting him, or when he tried to leave to support the female elder.
He has tried everything so far, using his yang radiance to burn the women resulted in a clash between some kind of blue flames that came from the light blue haired girl, what surprised him more was that in a direct confrontation, his yang radiance which should be at the middle Void Manipulation level actually lost.
Not only they lost but somehow, they became fuel for the blue flames that started advancing towards him creating a path through his radiance.