Even if Wei Ying omitted it, he already knew how dangerous the paperman technique can be, as there's a risk of insanity. Such as the demonic cultivation path that Wei Ying practice.

"Wei Ying, that was dangerous. And it doesn't take much for me to figured he's already messed up in the head."

Afterward, he fell quiet. Either way, cake done, plate taken away, and normal milk tea is brought and served for both, so it can be a complement for the cake.