Just did and it behaves as expected for me in the Android app (ie. not the dark pattern you described)

I can confirm it's grey on both sides on the website.

I get blue (on) / black (off) on the website. Or blue / white in light mode.

https://claude.ai/settings/data-privacy-controls

It was easy to not opt-in, I got prompted before I saw any of this.

I think they should keep the opt-in behavior past Sept 28 personally.

They’re likely A/B testing the interface change, which is why people are getting inconsistent results