Gemini conversations, including uploads, with human review of samples.
The part almost everyone misses is what turning it off does not delete.
Gemini Apps Activity: your prompts, uploads, and location context. A sample is reviewed by humans and kept separately.
Conversations already selected for human review are retained for up to three years and are NOT deleted when you turn the setting off or delete your activity. This is the single most misunderstood opt-out on the list. Say so plainly in the UI.
Workspace Gemini and Gmail smart features are governed elsewhere. See the google-workspace skill. Turning this off does not turn those off.
Turning the activity off does not delete samples already selected for human review.
Every service on that list buries its opt-out somewhere different. Don't Train On Me puts all of them in one checklist in a panel beside your browser, walks you through them one at a time, and helps you confirm your privacy settings on the ones that expose a setting it can read. Free, no account, and nothing you tick leaves your machine.