Why are border fentanyl seizures down?

Fentanyl remains the deadliest drug in the United States. But at the US-Mexico border, something unexpected is happening. Seizures of the synthetic opioid have fallen sharply - more than 50% compared to last year. But what's behind the drop? The World's Tibisay Zea looks at what the numbers can - and can't - tell us about the state of the fentanyl crisis.