Grids are very likely to appear, especially in the sky. My workflow is simple, load FluxFill with lora removal_timestep_alpha-2-1740, and then quantize transformer and T5 to FP8 precision. The task is to erase the person in the image.
It might because the image is too large for flux. You might scale the image to 1 mega pixels and try again. Tried with the closed source version. Seems a bit weird.