Apps launching at boot time. In particular, WhatsApp

I’m running /e/ v2.9 on a Murena CMF 1; and I have installed Startup Manager.

How do I stop applications - in particular WhatsApp - from launching on startup? All of the literature refers to Settings → Apps → Autostart which is not present; listing whatsapp in StartupManager “kill on startup” has no effect and I’ve been through the other options like disabling notificaitons.

Whatever happens, Whatsapp is stubbornly running when I restart the phone.

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