Edit: I know it's not really Scarlett Johansson, but it does sound very similar, and they can do better to make it right, in terms of sound and legality!
This is the case for all mobile and web apps and has been the norm for over a decade now. If you want control over the UI or functionality, use local software that doesn't check some server for feature flags.
Even if Scarlett Johansson would agree to license her voice, which is a big if, it's not her voice that's being removed. It's a different actress that some users thinks sounds like Scarlett.
https://openai.com/index/how-the-voices-for-chatgpt-were-cho...
I'm not saying it's her voice. I'm not disputing that they found someone with a similar sounding voice. But OpenAI should still aim to license from Scarlett Johansson and fine-tune on real licensed audio from her, the real deal, and let users switch to it if they want to.