The introduction of completely novel hardware inevitably brings the unexpected when some among the millions of new users do things that engineers hadn’t anticipated. One failing in M1 Macs is the common situation in which an external startup disk is removed when that Mac is shut down.
If that disk was selected as the startup disk and is nowhere to be found when the Mac next boots, the result is catastrophe; it panics, causing another boot, which leads to another panic, and so on until you force it to shut down, then start it up in Recovery.