Here's an example of a decline in living that persisted in the long-term, although it was a long time ago:
Britain experienced an economic collapse in the early 5th century AD after the Roman Empire left. Economic activity and urban life decided, and buildings were abandoned. Their supply chain was suddenly much more limited, and localized to specific areas, whereas before, the Roman Empire had allowed them to trade with other countries more. Their standard of living didn't really change for the next few centuries. I won't compare beyond that.
Britain experienced an economic collapse in the early 5th century AD after the Roman Empire left. Economic activity and urban life decided, and buildings were abandoned. Their supply chain was suddenly much more limited, and localized to specific areas, whereas before, the Roman Empire had allowed them to trade with other countries more. Their standard of living didn't really change for the next few centuries. I won't compare beyond that.