Fastai’s Resize has some randomness involved, so you’re not going to get the same image all the time and thus the difference in the logits. Were your model trained, you would get more or less the same predictions even if the model was fed different parts of the image, but your model’s body has random weights.
Try img.resize (although it results in a lower quality because it doesn’t maintain the aspect ratio), or seed PyTorch, NumPy, etc. for reproducibility.
Good luck!