Unfortunately some art files weren’t built correctly in 6.2 so they were showing up as brown squares, instead of the actual art. In order to fix this we had to rebuild all the art in the game, which requires all the art in the game to be redownloaded in 6.3.
We’re very sorry for the inconvenience and have taken measures to try to prevent art build issues happening in future updates.
Originally 6.3 was intended to be released last week but it was delayed on one of the platforms so we had to release this week instead.
We are making an effort to not release updates during Guild Wars weeks but this time it was unavoidable 
This is not something we included in the update.
Which screen resolution are you playing on?
Full screen or windowed?
Can you also please provide a screenshot?
Thanks!