Copyright violation would happen before LLMs yes, but it would have to be done by a person who either didn’t understand copyright (which is not a valid defence in court), or intentionally chose to ignore it.

With LLMs, future generations are growing up with being handed code that may or not be a verbatim copy of something that someone else originally wrote with specific licensing terms, but with no mention of any license terms or origin being provided by the LLM.

It remains to be seen if there will be any lawsuits in the future specifically about source code that is substantially copied from someone else indirectly via LLM use. In any case I doubt that even if such lawsuits happen they will help small developers writing open source. It would probably be one of the big tech companies suing other companies or persons and any money resulting from such a lawsuit would go to the big tech company suing.

IANAL, TINLA.