What happened

Observers reckon someone at Netflix took an existing piece of Arcane series art and extended it using Photoshop's "generative fill" tool (or an equivalent) to convert it into a banner. 

In response to the backlash, Netflix removed the poster and acknowledged that its use violated Arcane's strict policy against AI-generated content, which is intended to honour the human artists who contribute to the series.

Why it happened

Netflix's decision to use AI to promote the Arcane series appears to have stemmed from a need to cut marketing costs.

Riot Games' brand lead, Alex Shahmiri, said that the use of AI in this context undermines the hard work of artists and confirmed that it was a mistake. 

Netflix has not commented publicly on the fracas.