My understanding is that it's quite easy to poison the models with inaccurate data, I wouldn't be surprised if this exact thing has happened already. Maybe not an AI company itself, but it's definitely in the purview of a hostile actor to create bad code for this purpose. I suppose it's kind of already happened via supply chain attacks using AI generated package names that didn't exist prior to the LLM generating them.

One mitigation might be to use one company's model to check the work of another company's code and depend on market competition to keep the checks and balances.

Already happening in the wild