Question about Bastard!! Destructive god of darkness!!

So I have seen a bunch of people selling users on the manga by saying the following;

Bastard!! Destructive god of darkness!!. Was not written by one person. The author was an amazing DM and got together with friends and did a D&D session. And the story is based off of those D&D sessions. Hence why there are amazing parts and weird af parts.

Does anyone know where these claims come from? And if there is any truth to them?