This doesn't allow for logins to WT on mobile with TOTP codes.
The token input will soon no longer be on the login page anyway, but I am not sure how MobileFrontend renders extension special pages.
I think the best way of resolving this would be to fix: T74910: Getting rid of own login page (tracking)
@Florian won't https://gerrit.wikimedia.org/r/#/c/219754/ fix this?
That patch got merged.
If you enable $wgMFNoLoginOverride = true; in your LocalSettings it should work as normal. If not please file a new more specific bug.
Hope that helps!
@Jdlrobson: sorry for not responding here, but i'm in vacation and a bit busy :) But yeah, that will help, enabling this option for wikitech only sounds resonable, too.