Your n8n server is configured to use a secure cookie, however you are either visiting this via an insecure URL, or using Safari.
n8n 'Configured to Use a Secure Cookie' Warning Behind nginx: Redirect HTTP to HTTPS
Opening n8n over plain HTTP through nginx (http://repro.local:8081/) showed the full-page secure cookie warning, because n8n's auth cookie is Secure by default. A 301 from the HTTP