> But the AI is (supposedly) not making a copy of your painting.

You are mixing up the two things that I've mentioned in my original comment. You have to differentiate between creating a copy and creating a derivative work. Both of those things matter, when talking about AI, but the former is way more cut clear.

>The question is - to what extent does the exact image of your painting remain within the AI's data matrices?

And the answer is: It's irrelevant. The model has to be ingested with a copy of something. That's all that matters. The AI could even reject learning from that something. By the time that something reaches the AI to even do something with it, it's been copied (in the literal sense) who knows how many times, each of those times being a copyright violation.