The blurring appears harmless enough at first. When a Sim steps into the shower or otherwise disrobes, the game censors the virtual nudity by applying a blob of thick pixels. Normally this would vanish once the Sim is dressed, but EA's anti-piracy measures ensure that any illicitly obtained copies of the game instead cause the censorship blur to expand, eventually covering the entire screen. The end result is the messy swirl of pixelated colors that you can see above.
The discovery of EA's clever anti-piracy strategies has not gone unnoticed by pirates, many of whom have taken to the game's official forums (link may not work as EA's forums have been displaying errors all morning) to complain about their "broken" copy of the game. Despite the complaints, EA tells Joystiq that it has no plans to aid those players unable to enjoy their pirated copies of The Sims 4. Instead, the publisher urges affected players to purchase their own copy of the game which should lack the telltale pixelation.
The Sims 4 (Gamescom 2013)