OpenAI will add text watermarking too, but only in the EU, compared to Anthropic’s global rollout:

Over the coming weeks, we will introduce text watermarking to eligible ChatGPT and Codex users across all plans in the EU only. We are not making text watermarking a global default at launch. This regional approach gives us room to learn from real-world use and feedback.

I think this whole thing is largely misguided. Hope it is not expanded.