Three weeks ago I purchased SYMFONISK (Ikea)  speaker. Installed Sonos app, could connect also my Spotify account. As many know, the Sonis app is now dead/not showing any content - incl no Spotify.
 

when I start Spotify on my iPhone, it does not “see” SYMFONISK anymore. 

However - when I play music on Spotify, switch of from iPhone (black screen), and then get my iPhone, I can see on the welcome screen Spotify still playing.

I I then click on the “speaker icon” (red arrow points to it). This opens the following screen which allows me to select my SYMFONISK in my living room (now known as Unnamed Room). I can now stream music