I tested myself this demonic candy balls, more than 150+ in like 2 hours, giving them for free around thais. No one turned into the Mutated Pumpkin. So I think this effect is false. Otherwise, it could be that people reported this effect after being facing the actual Mutated Pumpkin and eating the candy while they were transformed by the Pumpkin. So, what I mean, is that the real effect would be to make you keep the transformation you got by one monster.