The Second Name, Qing Fu

Fang Jinyu was certain that the little girl wasn't reincarnated after failing to break through the Nascent Soul stage. It was because after the little girl disguised herself as an early-stage Qi Condensation cultivator and successfully obtained the identity card of the Tianling Sect, he saw her name on the card—Qing Fu.

Qing Fu claimed that she suddenly thought of it and she used it as her name because she couldn't forget it no matter what.

However, the book once mentioned it.

There was a mysterious split soul of Su Yier. When Su Yier returned from the apocalypse, it suddenly run out to take something, causing her to be in danger and almost die.

Although Su Yier managed to escape from danger in the end since she was the story's main character and even obtained a huge benefit, she was still dissatisfied with it.

Thus, the mysterious split soul explained the reason.

It was because it had discovered something related to its donor.