Smush made all my images blurry/poor quality – how to reset?

Hi there,
I just noticed that Smush must have stopped working at some point, and I had 400+ files to optimise. So I set about bulk-smushing them.

After it was finished, all my images were visibly reduced in quality, and some of the older ones in particular are downright blurry.

Around the same time, I turned on Jetpack’s site accelerator CDN thing (formerly Photon), then turned it off when I realised it might conflict. I’ve cleared all the caches, tried disabling Smush and Jetpack, and nothing will restore my images to their former quality.

I also tried regenerating all thumbnails using another plugin, but that didn’t help seem to help – they’re still blurry. Only the original image, or a custom size (not thumbnails) displays clearly.

Any way I can reverse the smushing/fix this?

Many thanks
Richard

The page I need help with: [log in to see the link]