Confusion about the prediction (C_pred) of the diffusion net

[Jay-Huy]

Thank for awesome invention, but i have confused how the equation generates predicted noise !!!
To be more specific, let's see

Firstly, the paper said that
C = -1 * x_0
So why then C_pred = pred instead of C_pred = -1 * pred

And if anyone have the answer, i will quietly appreciate so much
Thank for reading my issue