The death of Wi-Fi and Bluetooth
The Wi-Fi 6E & Bluetooth 5.2 controllers in my motherboard died today.
Until the motherboard can be replaced, the solution is to disable both in the UEFI BIOS. This is the only state in which the PC boots normally. Enabling the Bluetooth controller causes the boot process to spend about a minute trying to initialize the device, enabling the Wi-Fi controller causes the whole system to freeze with at the login screen and/or eventually reboot itself.