MPRIS notification does not respect MPRIS API
GNOME Shell 3.34.2
When an MPRIS client does not provide a mpris:artUrl attribute, GNOME Shell uses previous one.
This is not what API says: The location of an image representing the track or album. Clients should not assume this will continue to exist when the media player stops giving out the URL.
So, GNOME Shell should not show any cover if attribute is missing.