The cover art box considers the screen scaling to render the cover art in the proper resolution. E.g. on a High DPI / retina display with a scaling factor of 2 it will render the images in twice the displayed size.

But this code does not consider multiple screens with different scaling factors. If there are multiple screens the scaling factor of the primary will be used for all screens. This can result in pixelated cover art display if the Picard window is on a a screen with different scaling factor. E.g. the attached screenshot shows the Picard window on a screen with scaling factor set to 1.25, but rendered with a scaling factor of 1.0 (from primary screen). If the primary screen is changed to the one with 1.25 scaling factor the cover art will render nicely on this display, but when moving the window to the one with 1.0 it will look pixelated again.