Unwanted Data Use

[KMSongs]

Thank you for taking the time to read my question.

I have a Samsung Android phone and it seems that Spotify is playing songs on my phone when my children play songs at home on our Echo Dot.

When they play songs on the Echo Dot, I can see them playing at the bottom of my Spotify mobile app screen.

I purposely do not use my Spotify app with mobile data as I don't want to use up my plan. I only use it at home on our Wi-Fi, however I have 879MB of mobile data use this month already.

What setting do I need to change on my phone or account so that songs played at home on the Echo Dot do not play on my phone and use mobile data?

Thanks!