Version 3.0.0-1 of neutron-vpnaas-dashboard is marked for autoremoval from testing on Tue 11 May 2021. It depends (transitively) on horizon, python-novaclient, affected by #983853, #986143. You should try to prevent the removal by fixing these RC bugs.
A new upstream version is available: 18.0.0~rc1high
A new upstream version 18.0.0~rc1 is available, you should consider packaging it.