By default, CCC does not attempt to make backups of the startup disk bootable. When you configure a backup of your startup disk, CCC will back up the contents of the Data volume. That's all of your data, all of your applications, and all of your system settings – everything about your Mac that is customized. You don't have to be able to boot your Mac from the CCC backup to restore data from it. You can restore individual files and folders using Finder or CCC while booted from your production volume. If you ever need to restore everything from a non-bootable backup, you can install macOS via Recovery mode (e.g. onto a replacement disk), then migrate data from the backup via Migration Assistant. CCC backups are compatible with Migration Assistant, and we support that configuration.
Can I still make a bootable copy of my startup disk with CCC?
Yes. That functionality is still part of CCC, and will remain available within CCC until Apple breaks it for good. See Creating legacy bootable backups of macOS for more information on how to configure CCC to make bootable copies of the startup disk.