The Pis, and especially the compute module forms, are used for more than just clasroom toys and low power geek desktops. The CMs are a long term support item that, in recent forms, are FCC certified with wireless. Because it's a "module," with onboard wireless/antenna/etc, you don't have to perform the (quite expensive) certification tests for a wide range of products that can then have a perfectly good little computer and wireless in them.

Unfortunately, when those aren't available, it's a problem for not just those who want Raspberry Pis, but for everyone who wants to buy or sell any of those products based around a Pi. You can't just trivially redesign to anything else, not that there's anything else available...

I'm trying to build some YARH handhelds for various projects, and outside the stock of Pis I have a few of, that's just going to end up on hold, because I can't get any of the boards I figured would regularly be in supply places.

It's another breakdown of JIT.

My understanding is not that demand has gone up, but that availability has gone down.

Mostly lack of new PIs being produced.

Semiconductors shortage becomes a pain in the ….