Is there any evidence that this has actually happened?

Even if there isn't (yet?), there's probably someone who's honestly thinking this is potentially a viable business model and at least napkin-mathing it out.

My napkin mathing is that their ROI would be negative. That's a lot of compute and bandwidth they'd have to pay for even if they were just throwing away the results.

So, it hasn't happened, and you're just making stuff up.