As Blizzard has stated on multiple occasions, the mature language filter is NOT there to allow you to say whatever you please without repercussions.
https://us.forums.blizzard.com/en/wow/t/can-you-get-banned-for-swearing/285833/6
If you wish to appeal your silence, you will need to submit an appeal ticket.
Also, you can read up on the Code of Conduct for the game.