Sorry for the late reply. For the new Linux 6.6, the package linux-headers-rpi-v8 contains the needed headers and build link. It is a meta package like linux-image-rpi-v8, depending on the actual latest versioned headers package, linux-headers-6.6.74+rpt-rpi-v8 at the moment. When a new kernel is pushed to the APT servers, the dependencies will move to new versioned packages.
raspberrypi-kernel-headers is the old headers package for Linux 6.1.