Do not adjust your monitor; you're playing a pirated version of The Sims 4.
The Sims 4 features an antipiracy trap that cripples its visuals with an expanding, pixelated censorship blur that begins whenever a Sim removes his or her clothing (for example, when they're getting into the shower). When they get dressed, however, the blur doesn't go away. In fact, it gets bigger, eventually covering the entire screen.
Electronic Arts told Joystiq this isn't a glitch, it's intentional and it targets pirates. Pirates have shot back that they'll find a way to crack this, too, but for now, it's created the amusing, self-unaware irony of seeing some complain about it in The Sims' official forums.
Game developers have messed with pirates in the past, including unbeatable glitches in Batman: Arkham Asylum's Scarecrow level, siccing an immortal pink scorpion on pirates in Serious Sam: BFE, and Game Dev Tycoon, in whichpirates have their virtual games virtually pirated until they go out of business.