Comment by microtonal

Sure you can have data loss. But we were talking about updates. Most image-based systems do not update in-place, but write the updated system first and flip the switch atomically when the update is successful. macOS 11 and later cryptographically verify the new on-disk system volume and boot into the old system if the verification fails:

https://support.apple.com/en-au/guide/security/secd698747c9/...

SSV not only helps prevent tampering with any Apple software that’s part of the operating system, it also makes macOS software update more reliable and much safer. And because SSV uses APFS (Apple File System) snapshots, if an update can’t be performed, the old system version can be restored without re-installation.