Where did you get that info from? According to Google's own docs as well as my own image generation tests via the API, it supports up to 4K natively for gemini-3.1-flash-image-preview (aka NB2).

It just defaults to 1K. But I didn't see anything in the docs stating that it's just a simple upscale for larger resolutions.

https://ai.google.dev/gemini-api/docs/image-generation#gener...