Can someone try out CCC and let me know if they also are having problems with it?
CCC (and other cloning software) is certain to have issues with BS because of the changes to signing/certification of boot disks. Wait for something on Mike Bombich's web site. CCC is only just recovering from the unannounced changes in 10.15.5, so I don't suppose there will be a new version until Mike is confident there will be no further nasties as the beta cycle progresses.