I have strong opinions on this
I think yes, not all age gap relationships are problematic BUT there is strong evidence that are problematic/ abusive in higher numbers than non age relationships particularly when the younger person is in their teens / early 20s when the relationship begins. And honestly if you're going out with 16year old and you're in your 20s there is something wrong there, not saying abuse or pervy but why aren't you with someone closer in age? The difference in life experience is staggeringly obvious (not all relationships, I'm aware there exceptions)