Ubuntu package bug? Where to report?

Is there a bug tracker where ubuntu/debian related package bugs are tracked?

(nvidia-persistenced (nvidia-compute-utils) requires libnvidia-cfg1 but this dep is missing in the control file => nvidia-persistenced fails to start.)

https://launchpad.net/ubuntu/+bugs

So http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/ is just a copy of …, what?

The structure and dependencies of the nvidia driver packages is defined by Ubuntu/Canonical. Nvidia is following those when packaging/distributing the drivers bundled with the cuda packages.
If the missing dependency is also apparent in the packages distibuted by Ubuntu, report to Ubuntu.
If the Nvidia packaged driver is deviating from the Ubuntu definition, report it here together with the exact package affected.