Is direct browser access to Remote GitHub MCP Server officially supported? Behaviour has changed recently

[insin]

Describe the bug

I was previously able to sucessfully connect to the Remote GitHub MCP Server from a private browser client based on v1.x of the MCP TypeScript SDK.

When I picked this up again recently, connection attempts were getting explicitly rejected with a 403.

Affected version

Unknown.

Steps to reproduce the behavior

Try to connect to https://api.githubcopilot.com/mcp/ with a browser-based MCP client using a PAT for authorization.

Expected vs actual behavior

Expected:

Successful connection?

Actual (as of late):

HTTP/1.1 403 Forbidden
Server: github-mcp-server-remote
cross-origin request detected from Sec-Fetch-Site header

Logs

N/A