Don't say, "stolen". It's the wrong word. "Copied" is closer but really, "trained an AI model with images freely available on the Internet" is more accurate but doesn't sound sinister.
When you steal something, the original owner doesn't have it anymore. AIs aren't stealing anything. They're sort of copying things but again, not really. At the heart of every AI LLM or image model is a random number generator. They aren't really capable of copying things exactly unless the source material somehow gets a ridiculously high "score" when training. Such as a really popular book that gets quoted in a million places on the Internet and in other literature (and news articles, magazines, etc... anything that was used to train the AI).
Someone figured out that there's so much Harry Potter quotes and copies in OpenAI's training set that you could trick it into outputting something like 70% of the first book, one very long and specific prompt at a time (thousand of times). That's because of how the scoring works, not because of any sort of malicious intent to violate copyright on the part of OpenAI.
Nobody's stuff is being stolen.
That's not "upscaling". That's having the AI color it in for you. Like a comic artist who has a colorer (person that literally does that).
Upscaling just makes the image bigger (resolution-wise). It uses the same exact technology as regular AI image generation though 🤷
There's degrees to everything. AI haters are at the point where they're arguing with digital artists over what counts as art and it's getting insane.