The Portuguese midfielder picked up a fifth booking in the competition this season during the closing stages of Saturday's 3-0 defeat to Bournemouth.
Our captain appeared to receive the caution for dissent, from referee Peter Bankes.
Bruno had been walking the disciplinary tightrope for a number of weeks, with the bookings he had received coming before the end of October.
Fernandes was shown yellow cards in August's meetings with Tottenham Hotspur and Nottingham Forest, a game in which he struck the winner with a late penalty.
He was also booked during home defeats to Brighton & Hove Albion and Manchester City.