An upgrade note has been added to the release notes:
After upgrading, you should run a Pulp data repair command to fully resolve Pulp RPM bug Incorrent sync of different NEVRA same location_href · Issue #4073 · pulp/pulp_rpm · GitHub (incorrect sync of packages with different NEVRA but the same location_href). See the updated release notes for the exact command: Add rpm repair tip for Katello upgrade by ianballou · Pull Request #4717 · theforeman/foreman-documentation · GitHub