I think this is a sensible kind of warning for the average consumer (ie. not necessarily the tech savvy audience here) who may not realise the full implications of this app and how their data could be used.

For many this app may be their first exposure to using ChatGPT and the nature of it being an app that looks like any other chat app on your phone may lead some to incorrectly assume some degree of privacy over what they share.

The article is right also to point out that the OpenAI's anonymisation can only go so far if users unwittingly (or deliberately) enter personal deatils into the chat messages directly.