An LLM, being a large database derived mechanically from its training data, seems to meet the definition of “derived work” as exists in most copyright legislation.

The output from an LLM, through the inference process, is also mechanically derived from that training data.

Lawmakers might try writing exceptions to please a stock market absolutely baying for hyperscaler growth. Despite that, it seems entirely viable that the copyright, held by humans on the training data fed to the LLM, continue to hold in the output derived from that input.

People saying it's “obvious the output has no copyright”, or people who act as though it's all free from any claim by the humans who wrote the works used as training data, are just showing their ignorance, it seems to me.