NGNIX enforce HTTPS

for my Webapp (Angular App) we are using NGNIX as web server. I have a task where I need to make sure all assets/images are loaded over HTTPS.

In the Browser Dev tools, I see the request is sent over HTTPS. However, the response location header is coming back as an HTTP URL (see screenshot below).

Here are the current NGNIX Configs:

server {
    listen       80;
    server_name  localhost;
    root         /usr/share/nginx/html;

    # kill cache
    add_header Last-Modified $date_gmt;
    add_header Cache-Control 'no-store, no-cache';
    if_modified_since off;
    expires off;
    etag off;

    # Enforce HSTS
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;

    # Disable iFrames
    add_header x-frame-options "SAMEORIGIN" always;

    # detect and reject CRLF
    if ($request_uri ~* "%0A|%0D" ) {
      return 400;
    }

    # Fallback to default language if no preference defined by browser
    if ($accept_language ~ "^$") {
      set $accept_language "de";
    }

    # Redirect "/" to Angular app in browser's preferred language
    rewrite ^/$ /$accept_language permanent;

    if ($uri !~ ^/(en-US|de)) {
      return 301 /$accept_language$uri$args;
    }

    # Everything under the Angular app is always redirected to Angular in the correct language
    location ~ ^/(en-US|de) {
        try_files $uri$args $uri$args/ /$1/index.html;

      # Add security headers from separate file
      # include /etc/nginx/security-headers.conf;
    }

    location /health {
      access_log off;
      return 200;
      add_header Content-Type text/plain;
      # Enforce HSTS
      add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
    }
}

Any help is highly appreciated. Thanks