What the cause of that?
The fabs, being 90% automated, is it really the coronavirus?
The cause is not simple.
There is nothing new, component crises come and go, some are worse than others.
Just 3 years (in 2018 if I recall correctly) ago was the sudden catastrophic shortage of MLCCs and the associated panic. Then it just self-rectified in about 3-6 months, as usual. There was no pandemic, no earthquake or large fire in any factory, no simple explanation like that.
It's just that in modern high-tech, making investments to scale up production is
extremely expensive, the payback period may be decades even if everything goes well.
So it makes sense to run all fabrication resources at near full power.
Now the problem is the finicky feedback loop with positive feedback mechanism; a small disturbance (drop in production; but can be just a slight increase in demand) causes unavailability, which causes panic buying and stockpiling, which causes more unavailability. And because neither demand is going down nor production is going up, and because production's already running at say 95%, if you increase it to 100% it takes
long to rectify even a short backlog of orders!
Regarding COVID, my understanding is that component manufacturers
expected decrease in manufacture of electronics, i.e., orders going down, and reduced production to avoid overproducing. The opposite happened; people started buying electronics more than ever to spend time in lockdown. I'm sure production is mostly back to 100% already, and demand is already down to normal levels, but it will take months to get back into normal availability numbers.
ST's strike in France didn't help but is only a small part of the story, actual fab is obviously not in France.