From Carbon Copy Cloner 5.1.22-b1 release notes[0]: "This build continues our beta testing cycle for macOS 'Big Sur' 11. In the current macOS beta, CCC will cr

From Carbon Copy Cloner 5.1.22-b1 release notes[0]: "This build continues our beta testing cycle for macOS 'Big Sur' 11. In the current macOS beta, CCC will create Data Volume backups of any Big Sur startup volumes. Apple's APFS replication utility is not currently capable of replicating a Big Sur System volume (as of Big Sur Beta 6). We're working with Apple to develop the functionality within macOS that will allow third-party backup applications to continue making backups of macOS System volumes. In the meantime, we're making complete backups of your data, and those backups can be seamlessly used alongside the macOS Installer or Migration Assistant to produce a bootable backup or to facilitate a restore." [0] https://bombich.com/software/updates/ccc5_rn_beta.html https://bombich.com/software/updates/ccc5_rn_beta.html