dashboard_task.subscription.subscribers[].destination_id does not appear to support Lakeflow dynamic value references such as {{input}} or {{input.destination_id}}. Public docs show dynamic values for For each inputs and nested task parameters, and dashboard-task parameterization is currently documented for dashboard filter values, not subscriber destination fields.

That’s why a bundle-resolved value like ${var.destination_1_nonprod} works, while the runtime {{input}} form validates as a string but does not result in delivery. At the moment, the safe pattern is to emit one task per concrete destination ID (or generate those tasks ahead of deployment), rather than trying to parameterize subscription.subscribers[].destination_id at run time.