Fuzzy images and non-working lightbox plugins

I am unsure if this is related to the upgrade to 4.4, but I have only recently noticed the issues. On my last few posts, either all, or only some of the images in the post appear fuzzy and pixelated on a retina screen. I have tried replacing the image, regenerating thumbs, replacing the image with one with a different image ratio, switching themes, deleting and deactivating plugins, and even using a different image editor to compress the jpgs before upload, but no lock at all.

On this page https://sjp.id.au/adapted-lenses/lumax-c-mount-lens/ the pink third image down is pixelatred on retina screens while the others appear fine. I have replaced the image a few times but it is the same. On this page https://sjp.id.au/adapted-lenses/bokeh-lens/ they are all fuzzy. I have tried different image sizes, but nothing has worked.

The othger issue is that my lightbox plugin – foobox – has simply stopped working around the same time. I have even tried different lightbox plugins but they behave in the same way. Older posts are fine, but newer posts the images seem broken.

I have tried it in different browsers, but the lightbox plugins continue to fail.

I have tried reinstalling 4.4, but no change in behaviour for either problem.

It is very frustrating, as I seem to have exhausted all possibilities at my disposal.