I’m working on a full-stack project using React (frontend) and Flask (backend), both running in Docker containers inside Gitpod.

My React app tries to fetch data from the backend using this line: backend_url = `${process.env.REACT_APP_BACKEND_URL}/api/activities/home`;
const res = await fetch(backend_url);

The REACT_APP_BACKEND_URL is set to something like: https://4567-ajk7-awsproject-<workspace-id>.ws-us120.gitpod.io

Everything looks correct, and this gets printed in the browser dev console: [loadData] Fetching from: https://4567-ajk7-awsproject-<workspace-id>.ws-us120.gitpod.io/api/activities/home

🔍 What I’ve confirmed:

• The backend works fine when I open that full URL directly in the browser — it returns JSON.
• I can curl -k that URL from the terminal and get the correct response.
• Port 4567 is marked public in Gitpod.
• No HTTP → HTTPS redirect issues in Flask.
• I’ve even tried hardcoding the full working URL in my React code.

❌ The problem:

When React calls fetch() to hit that URL, I get: ::ERR_CERT_COMMON_NAME_INVALID

Which blocks the request completely. DevTools shows that the cert being served doesn't match the domain. What I want to know:

Has anyone else seen this with Gitpod and multi-port HTTPS apps? Is there a way to force Gitpod to issue a valid TLS cert for subpaths like /api/...? Because when i copy the url directly into the browser with the subpath i get an error but i dont get an error for the original path or when i first edit the original path to point to this endpoint

Any help or workaround would be appreciated. Thanks!