https://arstechnica.com/gadgets/2021/07/google-pushed-a-one-character-typo-to-production-bricking-chrome-os-devices/

Google says it has fixed a major Chrome OS bug that locked users out of their devices. Google's bulletin says that Chrome OS version 91.0.4472.165, which was briefly available this week, renders users unable to log in to their devices, essentially bricking them.

Chrome OS automatically downloads updates and switches to the new version after a reboot, so users who reboot their devices are suddenly locked out them. The go-to advice while this broken update is out there is to not reboot.