When resizing on displays of different resolutions and/or aspect ratios, the Windows 10 Desktop Application version 188.8.131.521.gb2f539fc has issues rendering on a different display: specifically maintaining original aspect ratio and resolution.
What I have done: I have 2 displays of 1920x1080 and 3840x2160, when Spotify opens on the 1920x1080 display, moved to the 3840x2160 display, then maximized, the application only renders up to 1920x1080 pixels, but is still interactable as if it were 3840x2160. See "spotify_resize_big.png". EDIT: Bottom Screenshot
The issue also occurs if the monitor is at a lower resolution and different aspect ratio: the application will only render up to the original aspect ratio based on the new resolution (not rendering the portion of the screen that is larger than the original aspect ratio). See "aspect_ratio_bug.png" EDIT: Top Screenshot