In "The New Three Kingdoms", why did Sun Quan call Cao Cao "Uncle Cao"?

This is deliberately pushing the Three Kingdoms into an idol drama. The screenwriter must hope that this can make the historical drama more popular, be more conducive to the handling of character relationships, and make it easier to intersperse plots of unofficial history and conflicts. Historically, at that time, the clans were divided and each dominated one side, so there was no chance of being so close. Sun Quan was raised by a nobleman, and then became the overlord at a young age. At that time, even the honorific title was just Prime Minister or Cao Gong, and he could not be called "Uncle Cao".