Issue with wordpress running in docker container and nginx used as reverse proxy

Question

I've moved an existing Wordpress blog to docker using the official wordpress and mysql images as shown below:

version: "3.9"

services:
  db:
    image: mysql:5.7
    volumes:
      - ./db_data:/var/lib/mysql
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: somewordpress
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: wordpress

  wordpress:
    depends_on:
      - db
    image: wordpress:latest
    volumes:
      - ./wordpress_data:/var/www/html
    ports:
      - "8000:80"
    restart: always
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: wordpress
      WORDPRESS_DB_NAME: wordpress
      WORDPRESS_DEBUG: 1
volumes:
  db_data: {}
  wordpress_data: {}

The server runs nginx as a reverse proxy, which does the HTTPS protocol termination and redirects the traffic to the docker container on localhost port 8000:

  location /blog {
      proxy_pass http://localhost:8000;

      # Do not buffer responses from proxied server
      proxy_buffering off;

      # The HTTP protocol for proxying (1.0 by default). Needs to be 1.1 for websockets and keepalive
      proxy_http_version 1.1;

      proxy_set_header Host            $host;

      # Forward the real visitor remote IP address to the proxied server
      proxy_set_header X-Real-IP       $remote_addr;

      # A list containing the IP addresses of every server the client has been proxied through
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

      # When used inside an HTTPS server block, each HTTP response from the proxied server is rewritten to HTTPS.
      proxy_set_header X-Forwarded-Proto $scheme;

      # The original port requested by the client
      proxy_set_header X-Forwarded-Port 443;

      # Defines the original host requested by the client.
      proxy_set_header X-Forwarded-Host  $host;
  }

When trying to access the blog from a web browser, the only resource that loads is index.php. All other resources like css and image files return 404:

What could be the reason for this?

Edit 1: result of listing /var/www/html from the wordpress container:

geschema@electrolite-22:~/docker/blog$ docker container exec -it ad276615ba09 bash
root@ad276615ba09:/var/www/html# ls -al
total 244
drwxr-xr-x  5 www-data www-data  4096 Jul 16 10:03 .
drwxr-xr-x  1 root     root      4096 Jun 23 07:22 ..
-rw-r--r--  1 www-data www-data   261 Jun 24 01:57 .htaccess
-rw-r--r--  1 www-data www-data   405 Feb  6  2020 index.php
-rw-r--r--  1 www-data www-data 19915 Jan  1  2022 license.txt
-rw-r--r--  1 www-data www-data  7401 Mar 22 21:11 readme.html
-rw-r--r--  1 www-data www-data  7165 Jan 21  2021 wp-activate.php
drwxr-xr-x  9 www-data www-data  4096 May 24 19:02 wp-admin
-rw-r--r--  1 www-data www-data   351 Feb  6  2020 wp-blog-header.php
-rw-r--r--  1 www-data www-data  2338 Nov  9  2021 wp-comments-post.php
-rw-rw-r--  1 www-data www-data  5480 Jun 24 01:56 wp-config-docker.php
-rw-r--r--  1 www-data www-data  3001 Dec 14  2021 wp-config-sample.php
-rw-r--r--  1 www-data www-data  5584 Jun 28 18:00 wp-config.php
drwxr-xr-x  6 www-data www-data  4096 Jul 16 11:42 wp-content
-rw-r--r--  1 www-data www-data  3943 Apr 28 09:49 wp-cron.php
drwxr-xr-x 26 www-data www-data 16384 May 24 19:02 wp-includes
-rw-r--r--  1 www-data www-data  2494 Mar 19 20:31 wp-links-opml.php
-rw-r--r--  1 www-data www-data  3973 Apr 12 01:47 wp-load.php
-rw-r--r--  1 www-data www-data 48498 Apr 29 14:36 wp-login.php
-rw-r--r--  1 www-data www-data  8577 Mar 22 16:25 wp-mail.php
-rw-r--r--  1 www-data www-data 23706 Apr 12 09:26 wp-settings.php
-rw-r--r--  1 www-data www-data 32051 Apr 11 11:42 wp-signup.php
-rw-r--r--  1 www-data www-data  4748 Apr 11 11:42 wp-trackback.php
-rw-r--r--  1 www-data www-data  3236 Jun  8  2020 xmlrpc.php

Edit 2: excerpt from the wordpress container logs, where we can see that only /blog returns the status code 200:

90.19.131.1 - - [16/Jul/2022:13:33:28 +0000] "GET /blog/ HTTP/1.1" 200 17386 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36"
90.19.131.1 - - [16/Jul/2022:13:33:28 +0000] "GET /blog/wp-includes/js/jquery/jquery-migrate.min.js?ver=3.3.2 HTTP/1.1" 404 35182 "https://example.com/blog/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36"
90.19.131.1 - - [16/Jul/2022:13:33:28 +0000] "GET /blog/wp-content/themes/twentyfifteen/genericons/genericons.css?ver=20201208 HTTP/1.1" 404 35182 "https://example.com/blog/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36"
90.19.131.1 - - [16/Jul/2022:13:33:28 +0000] "GET /blog/wp-content/themes/twentyfifteen/css/blocks.css?ver=20190102 HTTP/1.1" 404 35182 "https://example.com/blog/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36"