Testers say Google's next Flash-tier Gemini 4 model, under the community codename 'Gemini 4 Hydrogen', has been turning up in blind Arena matchups under the label gemini-3.8-flash since early November. One account puts the latest checkpoint on November 5. The codename follows the element pattern of Google's confirmed Gemini 4 Argon, announced September 30, and Gemini 4 Carbon, which followed in October — but Google has published no Hydrogen page, model card or announcement.

The demos cluster on speed: community testers report detailed 3D scenes, voxel builds and motion graphics finished in about 1 to 5 minutes, and in one Reddit side-by-side Hydrogen finished a motion-graphics prompt in about 2 minutes against about 11 minutes for Gemini 3.8 Flash. A separate leak reports the string gemini-4-flash-preview in tokenizer code in Google's public SDK repository. Every speed, price and throughput figure in circulation — including a rumoured 300–500 tokens per second and a guessed $0.75/$3.75 per million tokens — is tester speculation, not a measurement Google has published.

As of November 8, Gemini 4 Flash is not out: it appears in none of Google's Gemini API docs, model list, changelog or blog, and there is no official model ID, context window or launch date. Treat Hydrogen as an unconfirmed leak until Google names it.