Prohibition of soul flow?

I'm a little surprised by the words "Broken Nai". If this is a forbidden technique for soul flow, why does the Killer Team play this role?

Is it true that uuuuuuuuuuuu Did Murong Bing get the trick that the soul flowed out accidentally?

"That spell is called swallowing psychics..." Broken is frowned, "That's what the Vice-Chancellor of soul flow practiced, and he developed it himself. But because this technique is contrary to the principles of Qingyunmen, it is banned and people in Qingyunmen are not allowed to learn it. But tens of millions of years ago, swallowing psychics was lost in an accident.

So it seems...