In course of fledging out Wikimedia shareable Browserslist config, I've spotted that MobileFrontend relies on basic supported browsers with exception of pushing IE9 + IE10 out of the scope.
Proposal to remove IE11
I really don't see why MobileFrontend would not support IE_Mob, but does support IE11.
For sake of removing code legacy and possibly client performance for all others, I'd propose to remove IE11 from supported list.