I would define a dystopia as a world devoid of freedom.
In this definition, you don’t have to be imprisoned to lack freedom. In the Fallout world, the people lack freedom because they are all forced to struggle just to survive in the aftermath of a nuclear apocalypse. A world like Cyberpunk 2077 is very different since many people may live their lives in peace. It is still a dystopia as corporations have essentially taken over the world following a climate catastrophe. The people are second to profit and they have lost the freedom to control their own society. While it is very possible to live a wretched, fearful life in a dystopia, I don’t think it’s a requirement in all settings.
