In the past TDV allowed GitHub VCS connections to use username and password. This was changed by GitHub since introducing Personal Access Token.

TDV uses GitHub APIs to connect to its repositories, and with the new requirement from GitHub is in place to enhance security, it supports only Personal Access Token to access its repositories and perform any operations. The below snippet from the reference is for GitHub CLI, its the same for its API.

=====

HTTPS
You can work with all repositories on GitHub over HTTPS, even if you are behind a firewall or proxy.

If you authenticate with GitHub CLI, you can either authenticate with a personal access token or via the web browser. For more information about authenticating with GitHub CLI, see gh auth login.

If you authenticate without GitHub CLI, you must authenticate with a personal access token. When Git prompts you for your password, enter your personal access token. Alternatively, you can use a credential helper like Git Credential Manager. Password-based authentication for Git has been removed in favor of more secure authentication methods. For more information, see Managing your personal access tokens. Every time you use Git to authenticate with GitHub, you'll be prompted to enter your credentials to authenticate with GitHub, unless you cache them with a credential helper.

=====

All environments supported by Data Virtualization.

This article explains the requirement in using Personal Access Token with Username to connect to GitHub VCS repositories from TDV.

https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/about-authentication-to-github