It's hard to find good information on this subject but from the absence of non-US comments in this thread I'm inclined to conclude that supply chain disruption

It's hard to find good information on this subject but from the absence of non-US comments in this thread I'm inclined to conclude that supply chain disruption of the scale described is largely (not exclusively) a US problem. So it presumably has something to do with how US supply chains work compared to, say, Europe rather than being solely caused by the COVID-19 pandemic.