> "We" in this sentence refers to both parties

Fair enough.

> "they" refers to OpenAI. Not a grammatical error

I'd say it is. It's a press release from OpenAI. The rest of the release uses the third-person "they" to refer to Microsoft. The LLM traded accuracy for a bad joke, which is someting I associate with LinkedIn speak.

The fundmaental problem might be the OpenAI press release is vague. (And changing. It's changed at least once since I first commented.)