When connecting to a page that uses cPanel >> Directory Privacy the Force HTTPS redirection doesn't work until after the user enters the credentials.
in order to keep everything secure, including the transmission of credentials, these pages should also properly follow https redirection.
We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-40585. Follow this article to receive an email notification when a solution is published in the product.
There is no workaround available at this time.