Complete non-issue in my experience.

With usage on a daily basis since GPT-4 I have not once encountered a scenario where I was concerned about the output being complex enough and a verbatim copy to warrant such concerns.

Generally it would seem statistically unlikely to reconstruct a copyrighted work, rather the output should be a probabilistic average. Snippets are typically too common and short to be protected by copyright. Copyright challenges are likely to fail on the "substantial similarity" test.

I understand plaintiffs would need to show that code is virtually identical, not just similar, and that these parts represent a "substantial" portion of the original work's creative value.