The important part of the error is:

invalid peer certificate: UnknownIssuer

This points to a TLS certificate trust problem rather than a GitHub login problem.

If you're using a proxy, corporate network, VPN, or antivirus with HTTPS inspection, it might be replacing GitHub's certificate with its own certificate. VS Code then needs to trust the CA used by that proxy.

I would check these first:

1. Test the endpoint outside VS Code:

curl -v https://api.individual.githubcopilot.com/models

Look for the certificate issuer in the output.

2. Check whether your system trusts the CA:

curl -I https://api.github.com

If normal GitHub HTTPS requests also report certificate errors, fix the system CA store first.

3. If you're behind a corporate proxy, ask for the proxy's root CA certificate and install it into the OS trust store. Don't disable TLS certificate verification as a workaround.

4. Check the VS Code proxy configuration:

{
    "http.proxy": "http://proxy-host:proxy-port",
    "http.proxySupport": "override"
}

Use your actual proxy address. Also check whether environment variables such as HTTPS_PROXY or HTTP_PROXY are being set.

5. Restart VS Code after changing the certificate or proxy configuration.

I would not recommend setting TLS verification to false. It hides the certificate problem and removes an important security check.

Since the problem happens on multiple networks, I would especially check the local machine's CA certificates, antivirus HTTPS inspection, and proxy environment variables.

If curl -v shows an unexpected certificate issuer instead of a GitHub/recognized CA, that would be a strong clue about where the problem is coming from.