I woke up one day and seemingly overnight my beard had a grey patch - almost white, in fact. It fell out in the week after.
Almost a year and a half later, after leaving that job, I took the pandemic to really focus on my stress levels and be happier (I am). The grey patch is starting to fade away and some color is beginning to return. Certainly not the stark white that was there before, and definitely not grey either.
Idk if I believe it, maybe something else was happening. But it sure seemed stress related at the time.
EDIT: I'm < 30 and my family doesn't have a history of grey hair - quite the opposite. Forgot to mention this