Gemini 3. 6 Flash charges you for thinking tokens on top of the answer, and how many it spends is a dial you control per request. On the same 120-word writing task, the default setting billed $0.
Source: [Dev.to](https://dev.to/synthorai/gemini-36-flash-the-thinking-dial-that-moves-cost-30x-measured-3bhe)