Samsung has started rolling out a new feature for the Galaxy S10 camera called "Night" mode, according to SamMobile. It looks like a replacement for the original "Bright Night" feature that activated automatically (and only automatically) to let you take long exposures in very low-light conditions. With Night mode, you can decide when to turn the feature on and off, much as you can on Huawei's P30 Pro or with the Pixel 3's "Night Sight."
Source: Sammobile