The camera detects that your subject is mostly white.

So the camera will take a dark picture of you. At this time, you can set the aperture with m, such as F8 or F 1 1, and the shutter speed is one step lower than normal, or set the aperture with a, F8 or f1/,and the exposure compensation will be one or two steps.

The problem with lighting is that when you distribute light, try to fill it evenly.

Remember to shoot with a tripod, hehe.