I could always show that there exists some function f that produces said byte sequence when applied to my copyrighted material.
Can I sue Microsoft because the entire Windows 11 codebase is just one "rote mathematical transformation" away from the essay I wrote in elementary school?
Sure, the windows 11 codebase is in pi somewhere if you go far enough. Sure, pi is a non-copyrightable fact of nature. That doesn't mean the windows codebase is _actually_ in pi legally, just that it technically is.
The law does not care about weird gotchas like you describe.
I recommended reading this to a sibling comment, and I'll recommend it to you too: https://ansuz.sooke.bc.ca/entry/23
Yes, copyright law has obviously irrational results if you start trying to look at it only from a technical "but information is just 1s and 0s, you can't copyright 1s and 0s" perspective. The law does not care.
Which is why we have to think about the high level legal process that stable diffusion does, not so much the actual small technical details like "can you recover images from the neural net" or such.
I think the post you’re replying to saw was confused about the quote above. The person who’s claiming copyright by showing the claimed file started as their own image has to show that it started from their own image, and not just that the file could have derived from the image. Copyright cares about both the works and the provenance of works.
Stable Diffusion couldn’t be flagged under this pretense if a person used a prompt that was their own nor could they even be sued if they ran an image through it as long as there is no plausibility that it was made by a copyright work. The only thing I imagine a case working on is the actual training process of the algorithm rather than the algorithm itself for that exact reason.