https://www.bleepingcomputer.com/news/apple/macos-monterey-update-causes-some-macs-to-become-unbootable/

A growing number of Mac and Macbook owners report that their devices become unbootable after attempting to update to the latest version of macOS, codenamed 'Monterey.'

Apple released Monterey last week and made it available to all MacBook Pro and Macbook Air models that came out after 2015 and for the iMac (2015 and later) and the Mac mini (2014 and later).