US Copyright Office found AI companies breach copyright. Its boss was fired

I have yet to see someone explain in detail how transformer model training works (showing they understand the technical nitty gritty and the overall architecture of transformers) and also layout a case for why it is clearly a violation of copyright.

You can find lots of people talking about training, and you can find lots (way more) of people talking about AI training being a violation of copyright, but you can't find anyone talking about both.

Edit: Let me just clarify that I am talking about training, not inference (output).