This issue certainly persists in the current release (1.3.223), and does seem to affect some images more than others. Any updates on this issue @support?
Here is an example Discover screenshot:
Notice in particular that the Charlie Haden/Jim Hall album cover shows extreme jpeg-like distortion. Here is the Album page, where the image is nearly the same size, but looks MUCH better:
Also, the Seattle Symphony image is extremely blurry. Compare here to the Artist page:
The London Symphony image on the Discover page looks rather normal by comparison. There is definitely a bit of peculiarity in the image rescaling here.