Quick summary, Graeme Barber wrote the initial draft and turned it over to Wizards for playtesting with permission to let them make changes without contacting him. He acknowledges he didn't understand the process and assumed they'd still follow up if there were significant changes, so was surprised when the final version was missing major context, turned into a more linear adventure and had introduced what he viewed as problematic descriptions of Grippli as "primitive" and Yuan-ti as more evil for the sake of evil rather than having clear motivations. Due to the level of changes he's asked not to be associated with it.
His rundown of the situation was posted on his blog at
What Happened? Writing for Wizards Part 2 - POCGamer