The training process of LLMs is to copy the source material word for word. It’s instructed to plagiarize during the training process. The copyrighted material are possibly in one way or another embedded into the model itself.
In machine learning, there’s always this concern whether the model is actually learning patterns, or if it’s just memorizing the training data. Same applies to LLMs.
Can LLMs recite entire pieces of work? Who knows?
Does it count as copyright infringement if it does so? Possibly.