macOS methods for applications autostarting
Spotify uses a so-called Modern Login Item (in contrary to the deprecated Login Item).

The Modern Login Item doesn't require a classical daemon|agent.plist or a Login Item in System Preferences > Users &amp; Groups > $USER.

Apple dev guidelines require the apps using such modern login items to provide a setting in the preferences of the app itself to disable autostart though.

AFAIU the autostart is managed with a separate autostart app in the app itself and Apple's ServiceManagement.framework. In Spotify the app is: /Applications/Spotify.app/Contents/Library/LoginItems/StartUpHelper.app



Further reading and an example app with source code (compiling requires Xcode): Modern Login Item