From Github VSCode Docs:
GitHub authentication for GitHub repositories
VS Code now has automatic GitHub authentication against GitHub repositories. You can now clone, pull, push to and from public and private repositories without configuring any credential manager in your system. Even Git commands invoked in the Integrated Terminal, for example git push, are now automatically authenticated against your GitHub account.
You can disable GitHub authentication with the git.githubAuthentication setting. You can also disable the terminal authentication integration with the git.terminalAuthentication setting.
UPDATE: Refer to the solution here