Kids are like that too. There was some study that found ~50% of kids thought french fries were made from animals.
The correct conclusion is not that 50% of kids are dumb and 50% smart. Actually, none of the kids knew but they had a 50% chance of picking the right answer at random.
Knowing what you don't know is an "advanced" skill many adults haven't even mastered. I'm not at all surprised chatGPT struggles to not-answer questions on things you just made up.