I'm curious too, so I looked it up. https://developer.mozilla.org/en-US/docs/Web/API/Web_Authentication_API https://developer.mozilla.org/en-US/docs/Web/API/We

I'm curious too, so I looked it up. https://developer.mozilla.org/en-US/docs/Web/API/Web_Authentication_API https://developer.mozilla.org/en-US/docs/Web/API/Web_Authent... My guess is it's some JavaScript on the website, it would trigger the browser to ask the OS to prompt the user to provide their credentials.