If your renders appear splotchy/has smudges, this is usually caused by the Visual Settings, specifically those responsible for customizing the illumination.
As a first step, it is a good idea to make sure both Enscape and your GPU driver are up-to-date.
Afterwards, if the behavior persists, it’s time to review the Visual Settings. The most common cause is incorrect setup of the Exposure parameter. To be more specific, it is trying to compensate for a very dark scene. This causes Enscape to do a lot of “guessing” when it comes to the lighting and the shadows. More often than not, it’s the Auto Exposure being activated that’s causing the artifacts.
To address this, turn off the Auto Exposure and/or reset the Exposure to its default. Afterwards, make sure to adjust the light sources accordingly, to produce the desired illumination.
In general, a good practice would be to leave the exposure for the last stage, to fine-tune the look of your render, or to compensate for potentially insufficient lighting only marginally. It’s best to try to achieve the desired look first through the light sources and/or sun light, before resorting to using the Exposure or Auto Exposure.