The subredditor who posted the message, u/Huntstark also posted a screenshot of the message that was used to brick his/her console. It was also noted the message was sent during a game of Rainbow Six: Siege by a player from the other team who used a dummy account to send the message. 

It was noted that the crash was caused due to the inclusion of special characters that are invisible to the user, but were used to change the behaviour of the texts. There were 6000 invisible unicode characters alternating between ‘200E’ and ‘200F’, which are used to indicate left-to-right, and right-to-left writing. WhatsApp couldn’t process that many direction changes as they are all loaded into memory which has a physical limit.