Flashing light on the front camera on the iPhone XR

I don't own an 10R but I think that this will be my first phone I will buy because it has everything I need as a phone. Therefore, when I watch videos on Youtube about what it can do, I realized that there is a red light flashing at the front camera. I searched all over google and Youtube but there were nothing useful. The iPhone XR is the perfect phone for me except this annoying thing I can't figure out what it is