Generational memory.
Where the dragon is still in the egg and they already know about the outside world because they have absorbed some of the memories of their parents? Age of Fire dragons are all literally psychics so that makes sense. Golden Treasure does it because it needed a tutorial section and you know what that just works. Now there's this random LitRPG I jumped into with it too.
Where did this trope come from? Did it all independently arise in Dragon Media because half of them really want to start the book with them not even being born yet for some reason, but The Protagonist Is A Literal Infant is a bit of an issue? Or is there some Ur-Dragon-Media I am not aware of that started this trend?
Anyways with this sort of thing it really makes you think that if a dragon has its parents' memories, it might have a bit of their grandparents' memories, and so on and so forth, until there's a tiny little sliver of the life of the very first dragon to ever exist in all their descendants. Would that be crazy or what
In conclusion: dragons