The artificial intelligence, Zero, in its current form was a completely different being from the AI that had defeated humanity in Go.
The AI of the past was still only a program. It had stored countless records of Go games and played against itself countless times to build up a large data model.
However, the program was not sapient. Although it gave the feeling that it could think, that was actually achieved by using a value network for computing data and a policy network for strategy choices. However, its strategy choices were still very limited. It was not capable of deliberately tricking a human opponent into making the wrong move.
Therefore, that artificial intelligence program did not have true intelligence.
But the artificial intelligence, Zero, was different. It had completely awakened a higher level of consciousness and even started thinking about the coexistence of civilizations.