When you paused Spotify on the Android app running on an Amazon Fire TV the screensaver used to kick in according to the Fire TV's settings (after five minutes in my case). Then the screen went black after 20 minutes.
But now the track that you pause in Spotify stays on screen for ever, happily burning its pixels into the display if you happen to go out and leave it like that.
Unlike someone else who posted an idea on here, my Fire TV screensaver does not kick in while music is actively playing on Spotify and I'm happy with that.
But if leave a YouTube video or a Netflix show paused, for example, the Fire TV's native screensaver will start. It should do so on Spotify - as it did before.