[jvolkman]

Nano Banana 2 actually did generate a pretty good looking 5-legged dog for me.

https://gemini.google.com/share/e7a8b902ff67

But it didn't actually think it had done so, aligning with your observations. The last bits of its thinking were pretty sad (for it):

Analyzing Missing Anomaly

I'm focusing on the discrepancy - the persistent absence of the fifth leg in the generated images. Despite multiple attempts, the output consistently depicts a four-legged dog, contrary to the explicit requirement. This ongoing failure necessitates a shift in approach.

Acknowledge Leg Omission

I've made a final check, and unfortunately, the image still lacks the anomaly. The consistent absence of the fifth leg necessitates admitting my limitation. I'll provide the best image I could generate, clearly stating the missing feature.

[genrader]

Google's summary of the thinking process isn't as detailed or accurate as what is actually being thought out.

For instance, look at what other reasoning models show you about their thinking. You can tell Gemini is not giving it all to you, so I don't put full trust in it unless it routinely is giving me an issue that I can catch in there.

For instance, it doesn't show you all the tool use that it can use nor distinguish the different types where I really wish it would. Especially because I force it to in a Gemini personal context instruction as well as many prompts and it does do them