Nano Banana 2.5 Flash leak: Google's next image model is in the works

Google's image-generation lineup reportedly has another model on the way. A TestingCatalog report posted on September 5, 2026 says Nano Banana 2.5 Flash is in the works — the first public mention of the name, and it surfaced not as a launch but as one item inside a roundup about the Gemini desktop app turning into a "superapp." Read that item on its own terms: nothing about Nano Banana 2.5 Flash is confirmed, Google has said nothing, and no model has shipped. If the report is right, the new model would slot one rung above today's volume workhorse, Nano Banana 2 (the Gemini 3.1 Flash Image generation Google previewed in February and took to general availability in May).

Before going further, the sourcing honesty that a leak like this demands. TestingCatalog is the app-teardown outlet that first documented the Gemini desktop "computer use" plans in August and that previously caught an early preview card for Nano Banana 2 before Google previewed the model — so its reports have a real track record of being accurate. That is not the same thing as a release. There is no model card, no API listing, no date, and no pricing. Everything below labeled as the report is a claim about a product that does not exist yet, and everything beyond the name is our read of what it would mean, flagged as inference.

What we know — and what we don't

The entire public record is, so far, one sentence, and the honest structure for this piece is to keep the known and the unknown strictly apart.

• The name: Nano Banana 2.5 Flash, reported by TestingCatalog (@testingcatalog on X) on September 5, 2026, as "in the works."

• The context: the claim appeared in the same report that walked through the Gemini desktop app becoming an operating-system-level agent — "Ask" and "Assign" modes, computer use over chosen folders and apps, an Obsidian integration, and an "Ask Gemini" shortcut inside Fin. None of those carry Google confirmation either; the model item should be read on its own.

• The source's track record: TestingCatalog reported the Gemini desktop computer-use feature weeks before it became a story elsewhere, and it was among the first to surface Nano Banana 2's early preview card (under its GEMPIX2 internal name). Good history — still a report, not a release.

And the unknowns are the parts that usually matter more. We do not know the underlying model identifier (Nano Banana names are Google's marketing labels, not API ids — the current one is gemini-3.1-flash-image, not "nano-banana-2"), whether this is a brand-new checkpoint or a refresh of the existing one, what it would cost, which surfaces it would reach first, or whether the name survives contact with an actual announcement. Treat "Nano Banana 2.5 Flash" as a working label until Google says otherwise.

The name, decoded: a half-step in the Flash line

"Nano Banana" started as the internal codename for Google's first dedicated image-generation model and became the brand for the whole family. Where a "2.5 Flash" slot would sit is easiest to see against the lineup that actually exists today:

• Nano Banana (gemini-2.5-flash-image) — the original, launched August 2025 and the reason the codename stuck.

• Nano Banana Pro (gemini-3-pro-image) — the premium tier, announced November 2025 and at general availability since late May 2026; roughly $0.134 per 1K-resolution image.

• Nano Banana 2 (gemini-3.1-flash-image) — previewed February 26–27, 2026 and GA on May 28–29; the default image generator across the Gemini apps and API, at roughly $0.067 per 1K image, with up to 4K output, consistency for up to five characters and fourteen objects, and SynthID plus C2PA provenance by default.

• Nano Banana 2 Lite (gemini-3.1-flash-lite-image) — the budget tier, out since June 30, 2026 at a flat $0.034 per 1K image, capped at 1K resolution.

Read against that grid, a "2.5" reads as a half-step refresh of the Flash workhorse rather than the next Pro: same tier, aimed at the speed-and-price middle of the market, landing somewhere between the "2" and a future full generation. The "Flash" suffix is the meaningful part — it says Google is not positioning this as the quality flagship (that is Pro's job) but as the fast, cheap, high-volume default. On Google's recent image cadence a Flash refresh in the months after Lite is plausible, and a price somewhere in the $0.03–$0.07 per-1K band would be consistent with the tier. All of that is inference from a name, and the name itself is unconfirmed. Do not build a mental spec sheet out of a codename.

Why a Flash refresh would matter

If it is real, this is a meaningful price-and-quality event for the image API market rather than a curiosity, because the middle of that market is exactly where the pressure is. Nano Banana 2 defends Google's volume tier at roughly $0.067 per 1K image. Independently measured, it trails the quality leader — GPT-Image-2 sits around a 1,369 Elo on Artificial Analysis against Nano Banana 2's roughly 1,320 — while cheaper rivals attack from below: Qwen-Image-3.0 undercuts it at about $0.025 per image with stronger literal text rendering, and open-weight options like the LLaDA-Image family and Seedream keep the whole band's prices moving down. A refreshed Flash image model is Google's most likely answer on both axes: a quality bump and a price that holds the volume tier against the $0.02–$0.03 crowd. If history is any guide, image pricing moves in steps when a new Flash checkpoint lands — which is precisely why a router that passes vendor list prices through with no markup matters more as this market gets more crowded.

The superapp context is a reminder of where image models are going

The report that carried the model claim was mostly about the Gemini desktop app becoming a system-level agent: an "Ask" mode that answers and an "Assign" mode that takes control of your machine — running tasks across chosen folders and applications, with computer use that lets the agent operate other apps directly. TestingCatalog has also reported an Obsidian integration and an "Ask Gemini" entry point from inside Fin. None of that is verified, and none of it changes the image-model analysis above. But it is a useful reminder of where Google is pointing its models: image generation already sits in the Gemini prompt bar alongside video, and a refreshed Flash image model is the kind of engine a desktop agent would call when a task needs a visual artifact. Read the model item on its own — and watch how tightly the two stories get coupled if both turn out to be real.

What to watch — and what to do while you wait

Because the claim is a single source, the useful question is: how would you know Nano Banana 2.5 Flash is actually coming? The previous generation left a trail you can watch for again.

• A model id in Google's own listings. gemini-3.1-flash-image showed up in the Gemini API and Vertex AI model catalogs before the app rollout; the next id in the flash-image sequence would be the same kind of tell.

• A preview card in AI Studio or the Gemini app. Nano Banana 2 leaked that way — an early UI card under its GEMPIX2 codename, plus an anonymous arena entry ("anon-bob-2") that appeared on the image battle arena and was pulled. A new anonymous image entry is a classic early signal.

• A price in a provider or router catalog. When Google publishes image pricing, pass-through routers carry the vendor list price — which is how you will see the number without a markup on top.

• An actual announcement. Everything before that is rumor, including this article.

For builders, the practical move is the same whether the leak is real or not. You do not need to re-architect for a model that has not shipped. The current generation is callable today through OrcaRouter at provider list prices passed through with zero markup — Nano Banana 2 (gemini-3.1-flash-image-preview on the router), Nano Banana 2 Lite, and Nano Banana Pro are all one API call behind the same key, with automatic failover so a new or unproven model never has to carry a production path on its own. When a 2.5 Flash actually appears in a provider catalog, the same setup lets you route a slice of real traffic at it, compare it against Nano Banana 2 on your own evals, and fail back the moment it underperforms. That is the entire point of trying a rumor-grade model safely: no second contract, no code rewrite, and a vendor price cut showing up the same day Google makes it.

The honest bottom line is a conditional

This is a one-source leak, and the only defensible takeaway is conditional. If TestingCatalog is right, Nano Banana 2.5 Flash would be the next real event in the image-API market's volume tier — a Flash-tier refresh that could move both the quality bar and the $0.03–$0.07 price band within a quarter. If it is wrong, nothing has been lost, because nothing has shipped. The name is unverified, the capabilities are unknown, and no model card exists. Watch Google's model lists, the image arena, and the router catalogs for a flash-image id; ignore the hype; and when — or if — the model actually appears, test it against Nano Banana 2 on workloads that matter to you before you move anything.