Personally and IMHO - set the Catalina TM Drive aside for safe Keeping. Start a New Drive for Monterey
As previous person mentioned - the TM Backup with Catalina only has the items mentioned in that response. But least the TM Backup Drive with Catalina will be useful if one needs to get back to Catalina after a Clean Installation is performed.
Do you have a Rescue Plan In-Place. This comprises having 3 Backups using 2 methods and 1 Off Site incase of Theft, Loss or Natural Disasters. A Time Machine Backup is very useful and can be used to Revert to Previous Working macOS.
For addition purposes - two Tested Clones each to separate external drives. This is insurance incase the upgrades goes sideways. At least one Tested Clone and / or Time Machine Backup should be Off - Site
Does my CCC backup have to be bootable for me to restore data from it?