It looks like you're encountering issues with OAuth2 login using the WebBrowser control in your WinForms application. I recommend trying the Bee.OAuth2.WinForms package, which is designed to simplify OAuth2 integration with Google and other providers. It handles the OAuth2 flow and provides a seamless way to integrate authentication into your WinForms application. You can find the package on NuGet and refer to the documentation for setup instructions. It should resolve the issue you're facing.