Skimmed your linked paper. It seems they were able to classify hashes up to ~8% top-1 accuracy and ~30% top-10. Not exactly a blurred version, or any images at all.

So for example, they can say that you probably have images of trees, or images of buildings, but without much other data & very low accuracy.

I'd still be a lot more concerned about them simply flagging political images rather than trying to get a broad understanding of what type of photos I have