This is a minor naming issue, and doesn't affect game play, but even so, it shouldn't happen.
Basic Civ6. Playing Tomyris.
Philip (Spain) declares war on Trajan, and captures Rome. Several moves later, my advisor gives me a message that Spain has denounced Rome.
Basic Civ6. Playing Tomyris.
Philip (Spain) declares war on Trajan, and captures Rome. Several moves later, my advisor gives me a message that Spain has denounced Rome.