I was an anorexic teen and young 20something and though I am long recovered and take good care of my body now, I do not think I see what others do. We have one mirror in the house, though, that is so flattering. I will sometimes stand in front of it, naked, and ask my husband if I really look like that - I thought it was stretching me vertically; but he says yeah, that is exactly what you look like.
So my money is on lighting.
Also there used to be a saying (before filters) "the camera adds ten pounds". People look better moving around than frozen in time, even models, it's a thousand pictures and picking the best one.
I learned late in life, that it's okay to just not look some days.
i have this mirror cabinet in my bathroom. so some days, I just open it and look into the cabinet instead of my face.