"View menu (Gallery View) missing in iframe-embedded Web App for Pro account -- but works with Basic account. Same embed code

We embed Zoom Web App meetings via the meeting like in an iframe. Meetings hosted by our Basic account show the View menu and Gallery View inside the iframe. Meetings hosted by our Pro account hide the View menu inside the iframe, although the same Pro meeting shows Gallery View when opened top-level in a browser. What Pro account/user setting or feature flag controls the embedded Web App View menu? They are embedded into exactly the same application with the same code.