One guess I've heard, which I find aesthetically appealing but don't know if it's particularly true or not, is that there may be a number of circular dependenci

One guess I've heard, which I find aesthetically appealing but don't know if it's particularly true or not, is that there may be a number of circular dependencies in the global economy. COVID hits, and everybody cuts orders by 75%, runs production stockpiles down to zero, and lay off staff. The economy comes back three months later, and everybody tries to return to normal flow. But factory A depends on intermediates from factory B, which depends on feedstock from factory C, which needs a replacement machine from factory A... Meanwhile, the main customer for factory B won't actually be placing any new orders, because they pivoted entirely to making N95 masks. Now they have a warehouse full of product they can't sell, because the vaccines came along way ahead of schedule, and it's no longer the case that every person in the world needs to wear a respirator 8 hours a day. On top of this you can, if you're feeling malicious, sprinkle some critical parts sitting in containers in ships piled up at Long Beach, or in line behind Ever Given...