The apt.kitware.com for at least focal is broken currently, looks like cmake-data 2.24.0 is premature and missing. Using focal-rc works with 2.24.0~rc5 so it is specific to the “stable” version of the repository.
sudo apt install cmake Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: cmake : Depends: cmake-data (= 3.23.2-0kitware1ubuntu20.04.1) but 3.24.0-0kitware1ubuntu20.04.1 is to be installed E: Unable to correct problems, you have held broken packages.