You would normally be able to see javascript within the html, which you could view by Ctrl+Shift+I in Chrome. Or in Chrome you can press Ctrl+U to view page source code.
Anyway, I'm not sure it is javascript, it could be a layout issue that is causing it. Whatever, it is a non-trivial problem, and I would suggest asking at the Wordpress support site, where they might have a forum, or on Stackoverflow.
I include a few things I found after a quick Google, but it's non-conclusive:
Could be plugins?
On Android devices, the keybord disappears when opening the Search form dharbaliev (@dharbaliev) 6 months, 2 weeks ago For some times now, on Andorid devices, when I try to type someting in the Ser…
wordpress.org
Could be ordering of divs?
I am using Google Maps Js API and my input search bar works fine when I search for a place. When i use it via iPhone devices it works fine too, but when I use it via Android devices then the keyboard
stackoverflow.com