I have a fantastic LinkedIn photo, but it is now 6 years old.

I don’t know! I had a boss, briefly who’s linkedin photo looked like a different person. Like him before he went grey and gained 100 lbs. He swore the picture was 6 months old but that could only be true if he had like the most unhealthy 6 months in the history of human existence. So I think it’s best to update your photo every year or so, but take no action.