Fixes #4018 - Upgraded to 5.1.0: pending time doesn’t show a date.

db/migrate/20220318125144_issue4018_remove_old_translations.rb

@@ -0,0 +1,10 @@
+# Copyright (C) 2012-2022 Zammad Foundation, https://zammad-foundation.org/
+
+class Issue4018RemoveOldTranslations < ActiveRecord::Migration[6.0]
+  def change
+    # return if it's a new setup
+    return if !Setting.exists?(name: 'system_init_done')
+
+    Translation.where(source: 'FORMAT_DATE', is_synchronized_from_codebase: false).find_each(&:destroy)
+  end
+end

spec/db/migrate/issue_4018_remove_old_translations_spec.rb

@@ -0,0 +1,14 @@
+# Copyright (C) 2012-2022 Zammad Foundation, https://zammad-foundation.org/
+
+require 'rails_helper'
+
+RSpec.describe Issue4018RemoveOldTranslations, type: :db_migration do
+  before do
+    create(:translation, source: 'FORMAT_DATE', target_initial: 'Datum', target: 'Datum', is_synchronized_from_codebase: false)
+  end
+
+  it 'does remove old translations for source "FORMAT_DATE"' do
+    migrate
+    expect(Translation.where(locale: 'de-de', source: 'FORMAT_DATE').count).to eq(1)
+  end
+end