caching – React app served via Nginx/Docker shows stale JS & CSS in normal browser but fresh in incognito

My React app is served with Nginx inside Docker (with correct cache-control headers), but the outer server-level Nginx acting as a reverse proxy strips/overrides those headers, causing browsers to cache old files — which is why normal windows show stale content while private/incognito shows fresh content.

I tried:

Clearing browser cache (hard reload, emptied cache in dev tools).

Testing in incognito/private mode (which shows the correct fresh React build).

Clearing Nginx cache on the server, but caching is not enabled on the server’s Nginx config (only reverse proxy).

Updating cache-control headers in the React app’s Nginx config inside the Docker container.

What I see now:

Some updated JS files load correctly.

Some old JS files are still served.

Some CSS changes apply, but others still load the stale version.

I was expecting:

All JS and CSS files to update consistently in normal browser windows (like they do in private mode).

No stale content after deploying a new build.