A big part of it is increased demand caused by the disruptions themself: a lot of companies are now stocking to have enough to run production for the whole year, while otherwise they'd order just-in-time. That causes further reduced availability, which causes more companies to stock up, repeat ad infinitum.
It's a good theory, but I don't know how to prove it. Of course that's one cause. I'm concerned there are also cascading material shortage problems that have clogged up the system and may be preventing deliveries. I suspect NXP lost their 2022 fab slot for Kinetis micros, but no one is talking. Just delivery dates of late 2023. How many others did that happen to? Why? I am concerned China might be flexing their muscles by shutting down Shenzhen, and maybe they have been flexing their muscles for a year now. I am concerned there is a tipping point that we are close to, where it ALL just falls apart.
I don't have insider information or anything, but I'm convinced that packaging is a huge part of the problem. There are many more wafer fabs than packaging houses, packaging hits high-volume low-margin parts much harder, and everyone routes through the same (lowest cost...) houses in the same tropical low-wage countries because packaging dice is basically a commodity service.
Except that now there isn't enough capacity to go around.