For anyone following at home… the code in the ui that seems to do this is:
${stateObj?.attributes.restored && entityRegObj
? html`<ha-alert alert-type="warning">
${this.hass.localize(
"ui.dialogs.more_info_control.restored.no_longer_provided",
{
integration: entityRegObj.platform,
}
)}
</ha-alert>`
: nothing}
And from this thread: Restored Entities Explanation
“Restored” entities are present in your Home Assistant Storage Registry (they have been discovered in the past) but are not currently available/present/discoverable.
So it seems the thing to do is to look at the attributes of the entity, and if it has “restored” there, then it is “not provided” (and can presumably be deleted).