In Civilization VI, how do I liberate a city-state that was given to me as part of a deal to make peace?
I started a war with Japan, took their capitol and then they offered me a deal for peace that included ceding their capital and they also offered me Stockholm. I accepted the deal because they also offered a lot of gold, gpt and 4 or 5 luxury resources but only afterwards did I stop to think whether Stockholm was a city-state or not (I haven't met all civs yet).
The game never gave me the option to liberate the city. Is it still possible?