The fact that he knows this mushroom already, and that it has a fire attribute, is weird to me. Like sure, he knows it from his "previous" life, but we already established that he doesn't understand how living things can have attribute imbalances, from the earlier chapter where he was confused at how the girl could live if she had fire attribute (wondering if it meant her body had no water). If he knew about this mushroom being fire attributed already, he should already know it's possible for living things to be fire attributed, and it doesn't mean they just have no water in them.