From the perspective of the current version of the game there is no in game reason why his face is disfigured and from what I seen online there is no reference of it in the current game in books or cinematics. but what I have seen online there was cut content which explains how his face got disfigured.
I suggest three fixes for this.
1. Restore his act 1 appearance (simple and quick fix)
2. Give a simple mention for reason behind it for example it was a punishment made by a kithrak or inquisitor loyal to vlakkith which get referenced in sharesses caress.
3. Restore the content (if it exists) associated with it in a definitive edition or dlc.
Last edited by Krazark69; 19/01/24 12:15 AM.