While powerful, Nano Banana has practical limits: 
- Very low-resolution or highly noisy photos may not edit cleanly.
 - Extremely complex photorealistic lighting / reflections can be challenging to replicate exactly.
 - Tiny, intricate text or logos may not always render perfectly without manual touch-ups.
 - Copyright/ethics boundaries: it shouldn't be used to generate or edit content that violates rights or impersonates people without consent.
 - Edge cases: some highly specific compositing (e.g., exact physics-accurate shadows across multiple light sources) can require manual refining in an image editor.
 
Tip: For best outcomes, start with good quality images and, when needed, do a light manual polish after the AI step.