Chromecast interrupting webplayer/changing songs

[1sni_-osldtrd]

Plan

Free/Premium

Country

Device

iphone 8, PC, Sonos.

Operating System

(iOS 10, Android Oreo, Windows 10,etc.)

My Question or Issue

 When I have a playlist or song going, every now and then (moreso recently) the music will stop abruptly and change to something I have never heard of before. It then says the device making the change is Chromecast. As far as I know I dont use Chromecast. I only use my iphone 8, my PC, or my Sonos. I dont have any Android devices or Google home, so I'm really confused why it keeps switching on me. Feels like I cant control my playlist when I'm working out or at home and it has become more of an issue recently. I have tried uninstalling and reinstalling, and logging out and back in to my account but no luck. Thanks in advance for the help! 

[user-removed]

This is a longstanding problem, and even here a post can be seen from 2017.

How To Turn Off Web Player

Have been having the same problems, also have Chromecast. Spotify is playing **bleep** that isn't even on any of my Playlists or their recommended follow-up tracks after Playlist end.

Turned off Automatic Song after Playlist ends and also turned off Web Player, still it runs. Updated to the latest version just two days ago, definitely not the problem.