Old Zhou Baiyu was indeed surprised because he seemed to hear the voice-over of another himself.
And the expression of the new Zhou Baiyu gradually turned serious,
"I've always been thinking that the moment you appeared, it also meant that you'd traveled through time to a moment you had once experienced..."
"So, according to reason, you should also meet another you at this moment,"
"But you didn't encounter yourself, right? It is precisely because you didn't meet yourself that you didn't know the pollution source would grow rapidly later on, becoming a significant menace."
"So... in order to stop the impact of this menace and return everything to the beginning, you chose to use your privilege."
"That is to say, in your 'history', there was always only you."
Old Zhou Baiyu nodded; he understood the meaning of what the new Zhou Baiyu was trying to convey in an instant.
This sounded somewhat convoluted; this is one of the many "bugs" in the time loop.