HP Envy x360
Ubuntu 20.10 / Fedora 33
My Question or Issue
The app should request a dark theme so that server side decorations are not light when the GNOME is configured with its default Adwaita theme (or any other light theme). The combination of a light titlebar with Spotify dark contents is very unaesthetic and there have been a number of complaints regarding this for years.
Check https://gitlab.gnome.org/GNOME/gtk/-/issues/99, it's just setting a GTK property.