When refreshing the page or navigating back to the universal login page the email is autofilled but the placeholder does not go away. This looks like a broken experience. It is happening to me in Edge (chromium) Version 129.0.2792.89 (Official build) Mac (arm64).
Thank you for reporting this! Our Engineering team has identified this bug and will be fixing it, but I don’t have any ETA at this moment. I will make sure to update this post when I will have more informations.