A possible difficulty when using data augmentation in generative models is the issue of \"leaky augmentations\" (section 2.2), namely when the model generates images that are already augmented. This would mean that it was not able to separate the augmentation from the underlying data distribution, which can be caused by using non-invertible data transformations. For example, if either 0, 90, 180 or 270 degree rotations are performed with equal probability, the original orientation of the images is impossible to infer, and this information is destroyed.