As I understand it, Young Adult as a reading level is meant for ages 12-18.

I will take silly cheesy YA fantasy over old white man fantasy all day long

You know those aren’t the only options, right? There’s plenty of serious, adult fantasy written by women and non-straight, white, or old men. It’s fine to just prefer silly cheese, which it sounds like you do, but maybe just say that.

As for a recommendation, Robin Hobb has been mentioned elsewhere so I’ll throw in a series I think was criminally overlooked- God’s of the Caravan Road by K.V. Johansen.