Why an early win can hurt your protagonist
An early win on the thing that measures the war reads to your protagonist as proof their false belief about themselves was right.
If you can move your two sides somewhere else entirely and get roughly the same story, your setting is scenery rather than the conflict in physical form.
Move your story somewhere else entirely. If it's roughly the same story, your setting was never doing any work.
Your setting isn't a backdrop. It's your conflict in physical form. Every story argues against one destructive human trait, like greed or silence. That's what StoryDNA calls The Vice. The right place is that trait made big enough to see.
In Fahrenheit 451, firemen burn books instead of putting out fires. Shutting down thought becomes a job you do with a hose.
In Pride and Prejudice, the drawing rooms and balls leave a woman nothing to work with but her wit and her reputation. That's why every polite conversation is a fight to survive.
The place also decides what can happen at all. Tokyo in Lost in Translation allows one kind of loneliness and rules out one kind of scene. You can't have a shouting match with a stranger who doesn't speak your language.
Where a person stands decides what kind of courage is even open to them.
So try it. Move your story to another city, another century, another building. If nothing important breaks, your setting is decoration and your story still needs a real place to stand.
An early win on the thing that measures the war reads to your protagonist as proof their false belief about themselves was right.
The opposition has to reward the specific false belief your protagonist carries and punish the truth that would free them, or it is generic pressure.