The parent comment has a point. A layperson (or at least many people not read into this topic) isn't going to read the language in that privacy policy and come to the conclusion that "any private web page you ask Gemini about will be dumped into our training data". The text on Google's privacy page could absolutely be made more explicit.

I'm sceptical a layperson will understand or care what it means that their data will be used in training. If you are concerned about such things this heavily implies you don't want to share your data. Just don't agree to the terms and move on.