I came to the same conclusion as the authors after generating 1000s of thumbnails[1]. OpenAI alters faces too much and smoothes out details by default. NanoBanana is the best but lacks high fidelity option. SeeDream is catching up to NanoBanana and sometimes is better. It's been too long since OpenAI's gpt-img-1 came out, hope they launch a better model soon.
[1] = https://thumbnail.ai/