Some of this may be related to system volume signing, in which cryptographic signatures for the entire system volume are recomputed following an update. The ent

Some of this may be related to system volume signing, in which cryptographic signatures for the entire system volume are recomputed following an update. The entire filesystem tree is re-hashed recursively. Once the signatures are recomputed, the signatures are checked at each boot (which goes much faster, of course), and if verification fails, the system declines to start up. More info: https://support.apple.com/guide/security/signed-system-volume-security-secd698747c9/web https://support.apple.com/guide/security/signed-system-volum...