Mobile theme isn't supported much any more. No plans to really touch that portion of the forums, too much code that needs to be completely changed or reworked.
Thats fine, but it is the Default that someone gets with no previous login. So if I head over on my phone, I will never get the 2FA unless I KNOW to request the desktop as soon as the page loads. It happens before the login is complete and loads my preferred theme, so it will lock some people out. Is there any way to kill the default theme and force the desktop site automagically? If not, then maybe some sort of notice should be posted on that theme.