New EA LogIn?

I saw it once too - I don't know if it is correct or not but the address bar suggests it is.

It is the sign-in that you get if you sign-in via https://www.ea.com and the person icon.

The issued certificate for the login site is valid, so this seems to be in preparation of the new EA desktop app that is in open beta right now.

I'm on Tiberium Alliances Home Page and each button, one different login system:


Since a few days ago.

The link you label as 'new login' leads to https://www.ea.com/page/launch for me
The link you label as 'old login' shows two options: Launch leads to https://www.ea.com/page/ccta/launch?homePageUrl=/games/command-and-conquer/command-and-conquer-tiberium-alliances which is a much longer link.
Home leads to: https://www.ea.com/games/command-and-conquer/command-and-conquer-tiberium-alliances

I also got the new style screen when I had fully logged out and then logged back in via the person icon and the 'sign in' option it provides.

You're right, I should have indicated that I was referring to the position of the "Login" button and not the moment you are already logged in.

With the one on the left it always takes me to the new authentication system (which Elephterion said is in Beta) with the wallpaper in black and in the one on the right it takes me to the traditional system of the gray screen.

It looks to me like they are forcing everyone through the new ToS and privacy statements once, then it looks fairly normal.