axs

You were right!
I just chatted with my host and this was their reply:

Due to recent and ongoing attacks worldwide on WordPress sites, our server team has implemented secondary authentication to help reduce and prevent the attacks from affecting WordPress sites hosted with us. This is simply an extra security measure in place & does not mean your site has been compromised. However, for the time being, you will need to enter the username & password that appears before you will be able to log into your WordPress admin.

Thanks for the help!