Spotify starts up automatically - but I cannot change that?

After restarting my computer Spotify starts up automatically. The program is not shown in users - login items. There is no setting in the Spotify app I can change. The are no files related to Spotify in the User Library --> LaunchAgents or LaunchDaemons.

I also tried by rightclicking the icon in the Dock --> Options, switching "startup after login" on and off and restarting.

Annoys me that I have no control over this app. How can I stop Spotify form starting up automatically?

My OS is Big Sur 11.2