I had logged in on another tab, but instead of refreshing this page I clicked log in again. Instead of the little login UI, a mobile-like version of the homepage showed up.
The login modal currently uses a external page which is loaded in using iFrames. The page probably redirects if you’re logged in.
This shouldn’t happen anyways, since ROBLOX has headers which stop their website from being used in an iFrame.
I think that’s only the case for external sites trying to iframe roblox, although I’m not sure.
It’s like @Usering said:
When you’re logged in and you visit a login page, it returns you to the homepage.
(Unless there is some returnUrl parameter, then that parameter is used)
If you would go to roblox.com/newlogin while logged in, it does exactly the same.
(Better than wasting time logging in while you’re already logged in)