Coincidence?
Hey! That must be it. No more need to think about alternatives.
Causality is a tough nut to crack. I just thought so many new guns and so many new shooters "might" have something to do with the shortage. Yes I know there were reasons for the new gun rush and the new CCW rush and they both have the initials BO (and no, it isn't body odor).
It seems likely that the new guns and the new shooters (proven by the new CCW permits issues) points to a likely conclusion. But I sure can't say that is exactly what happened.
BTW there are a lot of new AR's in the world and one thing we might think about (to even further muddy the water) is that there have been a lot of .22 based AR type weapons sold in that same time period.
Mostly I'd say the ammo makers wanted to catch up on making centerfire first because there is a bigger profit margin there most likely. And the crush was made worse for rimfire rounds. I just hope it ends soon. I know it's mostly over but I want it completely over.