keycloak-js initialization failed because an ancestor violates the Content Security Policy directive: "frame-ancestors 'self' – Nginx

I have a NGINX (1.14.1) which forwards /auth request to Keycloak (14.0.0) running in a cloud.

Here is the NGINX configuration in /etc/nginx/conf.d/my.domain.biz.conf

server {
  listen 80;
  server_name my.domain.biz;
  return 301 https://$host$request_uri;
}

server {
  listen 443 ssl;
  server_name my.domain.biz;
  ssl_certificate /etc/letsencrypt/live/domain.biz/fullchain.pem;
  ssl_certificate_key /etc/letsencrypt/live/domain.biz/privkey.pem;
  location /auth {
    proxy_pass http://127.0.0.1:8080/auth;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_set_header X-Scheme $scheme;
    add_header X-Frame-Options "ALLOW-FROM https://my.domain.biz/";
    add_header Content-Security-Policy "frame-src https://my.domain.biz/; frame-ancestors https://my.domain.biz/; object-src https://my.domain.biz/;";
  }
}

I’m able to create a realm and a public client in the Keycloak’s admin console at https://my.domain.biz/auth/. I’m able to list the endpoints from https://my.domain.biz/auth/realms/myrealm/.well-known/openid-configuration

also, I have updated the following two values in security defenses of the realm settings,

X-Frame-Options: ALLOW-FROM https://my.domain.biz
Content-Security-Policy: frame-src https://my.domain.biz/; frame-ancestors https://my.domain.biz/; object-src https://my.domain.biz/;

I have a React webapp with keycloak-js 14.0.0 running on my laptop at http://localhost:8044/, which I want to authenticate with the Keycloak running in the cloud. The Keycloak client is initialized with the following keycloak.json,

{
  "realm": "myrealm",
  "auth-server-url": "https://my.domain.biz/auth/",
  "ssl-required": "external",
  "resource": "my-pkce",
  "public-client": true,
  "confidential-port": 0
}

and the React code snippet,

  const kc = new Keycloak('/keycloak.json');
  ...
  await kc.init({
    onLoad: 'login-required',
    pkceMethod: 'S256',
    enableLogging: true
  });

When accessed the webapp at http://localhost:8044/, it didn’t redirect to the Keycloak’s login page, with an error shown in the Chrome browser console:

Refused to frame 'https://my.domain.biz/' because an ancestor violates the following Content Security Policy directive: "frame-ancestors 'self'".

and only one line is logged in the NGINX’s /var/log/nginx/access.log,

"GET /auth/realms/myrealm/protocol/openid-connect/3p-cookies/step1.html HTTP/1.1" 404 2032 "http://localhost:8044/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.164 Safari/537.36" "-"

Do you have any idea of what could be wrong?