> If you try to do some kind of dupe-detection, someone can use a lightweight LLM to make superficial changes until it's considered a different project.

Even if you don't, a lot of source code can be legitimately copied thanks to the GPL/MIT/BSD/etc. I'm allowed to take all of zlib and integrate it into my own project if I so chose.

Yup, I just added something to that effect, sorry if my edit arrived after you replied.