Firefly repeating the same image and/or completely over-saturating it yet still using credits

I can only guess at the prompt you are using, and what the original image looks like, but in my experience if you are asking the AI to colorize it works better if you start with B&W.  If I ask the AI to improve the colour, I invariably have to desaturate the resulting image.  It’s all a learning process, and that means for you, me and the machine.