If you built a form (or simply a TextInputElement should work, too, to reproduce this) in PHP and set the `autofocus` parameter to true, this works without any problems, if you've disabled JavaScript (or don't infuse the element with `OO.ui.infuse()`). If you infuse an element with an autofocus, the (auto)focus is lost after the element is rebuilt in JS and replaced the original element.
The focus itself should remain on the last autofocused element in the DOM, instead of lost entirely in the form.
This could be more annoying if a user has a slow connection and the browser already focused the autofocused element and OOUI rebuilds it just a second later without to focus it again.
I haven't looked into a solution yet, maybe this is already a known problem and a workaround for it. I just recognized it while working on https://gerrit.wikimedia.org/r/#/c/225842/ :)