It is not. There are plenty of studies showing that LLMs spit out code that is near verbatim to existing code and LLM companies even go so far as to instruct their models to not also add the corresponding license/copyright headers with that code.

There are probably law firms analysing common code patterns LLMs often use right now and are approaching copyright holders of similar enough code to buy up the rights. It might not all stand up in court, but it will be enough to scare some people into settling for fee that guarantees a profit for these law firms. This is a tried and true method for an entire industry of law firms.