Using the 🍌Create Images tool on first generation bypasses Imagen

[floral raven]

The way I understand the image tools to work, and confirmed here by Laura (#✨┊gemini-chat message) is that the first-pass image generation is provided by Imagen, and any subsequent edits are 2.5 Flash Image/nano-banana.

However starting recently this doesn't seem to be the case.

In both web and mobile, if you purposefully select the 🍌Create Images tool, even first-pass images are generated with nano-banana (at 1K output). Currently the only way to get an Imagen 4 / 2K output is to NOT use the tool at all, and prompt "Create an image" or "Generate an image."

Here is an example without selecting the tool: https://g.co/gemini/share/52a2587d8c0d
The first image generated is Imagen 4; it is 6.1 MB and 2048x2048. The second edited image is nano-banana at 1.8MB and 1024x1024. This is correct.

Now, here is an image generated with the 🍌Create Images tool selected from the first prompt: https://g.co/gemini/share/2611de1e7b12. The first generated image is 1.3 MB and 1024x1024. In other words, nano-banana. This is not correct.

I am able to reproduce this behavior every time.

First image in first chat (above)

First image in second chat (below)

I regret the images themselves are very similar visually, but you can differentiate them by the rock/island in the middle of the water in the second chat