This is even if you're using it with a google account that has billing connected.
The fine print is here: https://ai.google.dev/gemini-api/terms
If I'm being uncharitable this is purposefully deceptive / a dark pattern to scoop up as much data as possible.
> Paid Services
>... When you activate a Cloud Billing account, all use of Gemini API and Google AI Studio is a "Paid Service" with respect to how Google Uses Your Data, even when using Services that are offered free of charge, such as Google AI Studio and unpaid quota of Gemini API.
>... How Google Uses Your Data When you use Paid Services, including, for example, the paid quota of the Gemini API, Google doesn't use your prompts (including associated system instructions, cached content, and files such as images, videos, or documents) or responses to improve our products, and will process your prompts and responses in accordance with the Data Processing Addendum for Products Where Google is a Data Processor. For Paid Services, Google logs prompts and responses for a limited period of time, solely for the purpose of detecting violations of the Prohibited Use Policy and any required legal or regulatory disclosures. This data may be stored transiently or cached in any country in which Google or its agents maintain facilities.
Activated a Cloud Billing account -> All use of Google AI Studio is a "Paid Service", even free use -> Google then doesn't use prompts or responses to improve the products