When you add a security key to SSH operations, you can use these devices to protect you and your account from accidental exposure, account hijacking, or malware, GitHub security engineer Kevin Jones ...
GitHub has added support for securing SSH Git operations using FIDO2 security keys for added protection from account takeover attempts. Researchers at North Carolina State University (NCSU) found [PDF ...
Since normal ssh commands work but git commands don't, I think it's a problem with git-for-windows, somehow. My current workaround is to add IdentityFile tag to ~\.ssh\config pointing to the right key ...