"Cold Blooded" is not a thing. Reptiles & amphibians are Exothermic, meaning they lack significant ability to maintain a single stable body temperature. They're still significantly hotter than the surrounding environment, and various groups have adaptations that allow for mimickry or partial thermoregulation (such as sharks & tuna having counter-current blood flow in their red muscles to keep heat inside the muscles, or most obviously feathers as first evolved among dinosauria). Mammals & present-day dinosaurians (birds) are on the other hand Endothermic. We have a target body temperature and loads of adaptations dedicated to maintaining that temperature. Indeed it is the need to maintain that stable temperature that has most well-defined our adaptation compared to the adaptation of reptilians, pisceans, and amphibians. The target temperature also varies substantially from species to species; our target of 98-99F is high compared to most mammals, and especially high when compared to non-placental mammals (platypuses, echidnas, and of course the marsupials). Indeed it is more accurate to describe an endotherm such as a platypus as "cold blooded" in human terms than a large exothermic reptile such as a nile crododile that naturally sits at a much higher internal temperature.

It would be more interesting to have your trait be labelled as "Exothermic" and to function as such, rather than the fantasy that is "cold blooded". It's not nearly as bad as saying "vaccines cause autism" but it's the same kind of mistake. Otherwise yet another fantastic mod!