Budget phones are cheap for a reason. Despite how companies try to spin them, they will always run out of hardware that allows this or that feature. Sometimes this type of hardware is something we generally take for granted. As environmental sensors that allow phones to automatically adjust their brightness depending on the environment. Samsung's Galaxy phones do not have this, but it seems the company has found a rather curious way to circumvent this limitation. All you need to do is take a selfie.
No, do not worry, the phone does not take a snapshot of your face and sends it to the Samsung servers. However, it will use the front camera to take a quick photo regardless of whether your face is there or not. And according to Samsung's notice, the photo will not be stored anywhere, not even on your phone.
So, here's how this is supposed to work. Turning on the previously missing auto brightness feature on phones that do not have an ambient light sensor will cause the phone to take a picture every time you unlock the phone. This image will be analyzed to determine the lighting condition at that time. Presumably, the photo is immediately discarded.
While this seems like a clever way to compensate for the loss of an ambient sensor, the way it adjusts brightness may not be so smart. It will combine the lighting condition you analyzed from the selfie with the brightness levels you set. In other words, you will have to train it manually for a while before you start doing things automatically.
At this time, the update that brought this feature was released only on the Galaxy J8. I hope it also reaches other phones in the Galaxy J series, but given Samsung, this is very uncertain.