I can only speculate that the model that generated the code hasn't undergone selective unlearning for verbatim data (SUV) or something similar. As you understan

I can only speculate that the model that generated the code hasn't undergone selective unlearning for verbatim data (SUV) or something similar. As you understand "sometimes generates verbatim code" and "just regurgitates [non-trivial] portions its input" are different statements. The possibility of SUV clearly shows that a model does more than "just regurgitating."