NoiseScheduler https://github.com/keras-team/keras-cv/blob/master/keras_cv/models/stable_diffusion/noise_scheduler.py contains a bug with default parameters. For a pretrained SD it must be: NoiseScheduler(beta_start=0.00085, beta_end=0.012, beta_schedule='scaled_linear', clip_sample=False). For now it is: NoiseScheduler(beta_start=0.0001, beta_end=0.02, beta_schedule='linear', clip_sample=True). As I understand it, this happened because of copy-paste with a hugging face (where the default parameters are taken for some old GANs).