In 2020 I was working for a consumer electronics company and went to some presentations on how our supply chain and operations teams were dealing with the pandemic. I'm far from an expert on this, but this is what I heard from people who were working on this.

First, you had a massive lockdown in China in January 2020, which shut factories temporarily. Then when those factories came back online, the production lines had to be reconfigured so that stations were 2 meters apart. At the same time, a lot of the collaboration that typically happens by people from a company flying out to China to meet with the supplier face-to-face were shifting to video, which frequently met that at least one side of the call was early in the morning or late at night. And as all of that was happening, there were also large shifts in demand as some products saw spikes in orders. That pattern then repeated itself across the world - a company might move production from China to, say, Indonesia, only to see the new factory have to temporarily shut down.

I can imagine that two years of this would create major backlogs and disruptions.