One or more dropdowns in [`app/assets/javascripts/diffs/components/compare_dropdown_layout.vue`](https://gitlab.com/gitlab-org/gitlab/blob/master/app/assets/javascripts/diffs/components/compare_dropdown_layout.vue) should be migrated to one of the new dropdown components. See the [parent epic](https://gitlab.com/groups/gitlab-org/-/epics/10695) for guidance on migration strategies.