This month I noticed (when I received a message from the service provider that the consumption was exceeded), that Spotify used much more cell data in the background than before. I have not changed the way and habits I use Spotify, and I know my data consumption in the foreground, but suddenly it turns out that background data has increased about 8-10 times.
When attempting to limit data consumption in the background through the phone's settings, Spotify stops working and/or waits for a long time until the next piece starts. I reduced the quality of music to "normal," but I do not see a change in consumption.
And one more thing - I'm listening to mostly 100-200 pieces that should be in Spotify's cache, which is over 6GB. Why not read the data from there, but download it from the network?
Spotify is regularly updated.