I have Spotify on auto-start when I boot my laptop and today I'm on a metered WiFi connection (the router is using 4G). Because it's a bit slow and has limited data I was checking out of curiousity in my Mac's Activity Monitor and found out that "Spotify Helper" downloaded about 100 MB of data just like 10 minutes after I booted.
I did not play any music and I don't have any offline playlists that started to sync. Last time I used Spotify was last night.
I tried turning on offline mode inside Spotify but it still kept on downloading whatever it was downloading. Can't see what it was doing. Why would Spotify Helper still download so much data in the background?
The Spotify helper and the whole app in general will try to sync up all your account data upon launch and regularly while the app is open and your device connected to the internet. We can't say for sure exactly what the app was trying to download initially, but this largely depends on how many items you have in your library and the song/ podcast quality you've set in the app Settings. Better quality will drain more data.
Offline mode should stop the app from connecting to the internet. This may not happen immediately though.
It's a good idea to run a clean reinstall of the app, following this guide. This way all app data will be wiped completely. I'd recommend doing this from time to time to assure that there aren't any issues caused by corrupted data.
Hope this info helps. Don't hesitate to reach out again if you have questions.
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