bizGyver™
Petit Tech for macOS
macOS has a function of backup named "Time Machine", but macOS Big Sur 11 or above can backup only the data such as data volume because it strengthens its encrypted protection for the system content including system volume.
This is why macOS Big Sur 11 cannot boot from its Time Machine backup, and also it cannot copy APFS volume group as backup by Disk Utility or Terminal.
However, macOS Monterey 12 or above can copy APFS volume group and APFS volume by Disk Utility.
In order to copy APFS volume group, at first, you have to boot on macOS Monterey 12 or above from either macOS Recovery or a bootable installer for macOS which you create beforehand.
You can also copy APFS volume group or APFS volume whose version is macOS Big Sur 11 or below by booting a bootable installer for macOS Monterey 12 or above.
However, you cannot copy APFS volume group or APFS volume which are formatted by "APFS (Encrypted)", "APFS (Case-sensitive)" or "APFS (Case-sensitive, Encrypted)".
You cannot copy APFS volume group or APFS volume as disk image whatever format they are.
macOS has a function of backup named "Time Machine", but macOS Big Sur 11 or above can backup only the data such as data volume because it strengthens its encrypted protection for the system content including system volume.
This is why macOS Big Sur 11 cannot boot from its Time Machine backup, and also it cannot copy APFS volume group as backup by Disk Utility or Terminal.
However, macOS Monterey 12 or above can copy APFS volume group and APFS volume by Disk Utility.
In order to copy APFS volume group, at first, you have to boot on macOS Monterey 12 or above from either macOS Recovery or a bootable installer for macOS which you create beforehand.
You can also copy APFS volume group or APFS volume whose version is macOS Big Sur 11 or below by booting a bootable installer for macOS Monterey 12 or above.
However, you cannot copy APFS volume group or APFS volume which are formatted by "APFS (Encrypted)", "APFS (Case-sensitive)" or "APFS (Case-sensitive, Encrypted)".
You cannot copy APFS volume group or APFS volume as disk image whatever format they are.