I have submitted Firefly images to Adobe and the success rate is not spectacular, particularly if including people in the image. Like all AI images you need to examine them closely before submitting.

I don't do much AI but sometimes I do a thing where I use Firefly to generate the main focal point of a planned image, then I take that into Photoshop and paste it into a larger canvas and gradually outpaint it with generative fill in 1024x1024 blocks for max quality. It works pretty well for wide angle landscapes. At the end I downscale the whole image a bit. Haven't had any rejections.