Can’t disable typing bar at bottom of screen

When I am using Firefox for iOS, and I click on any text input, a bar appears at the bottom of the screen. This bar contains nothing apart from ‘↑ ↓ Done’ on the right. This bar is really annoying and moves the page around irritatingly. If I click ‘Done’ it will temporarily remove the bar until I click on a text input again, and it will appear again. I would like to know if this is something to do with Firefox or the device iOS settings. This thread from apple discussions has the same problem: https://discussions.apple.com/thread/255143785?sortBy=rank A screenshot is attached.