Copyleft and the whole software licensing ecosystem only matter when producing that software actually requires serious human effort and dedication.
For my machine translation of SQLite to Go I added this to the README as to licencing:
Most of the code here is machine translated using wasm2go. As such, the original authors retain copyright and the original licenses remain in effect. Everything else is licensed under MIT-0.
The translator (wasm2go) has a licence chosen by, and a copyright notice from, me. Makes no sense for the translated code.
And avoid relying on direct LLM output for actual work to make sure I don't accidentally include some regurgitated snippet from an incompatible license.
It helps that LLMs struggle to write good, idiomatic code in my language of choice.
Fixed that for you. Code generated by an LLM is not copyrightable (because copyright only protects human effort), so the codebase is automatically public domain and cannot be licensed at all.
They could theoretically copyright the prompts that they used, but as that's not part of the output, and the output doesn't deterministically arise from those prompts, they'd struggle to use that to back a copyright claim.