Think it’s a the same exp tho. From what I’ve been told the exp is balanced. Lower dungeon gives less exp per kill but a better bonus at the end while higher dungeon gove more exp per kill but a smaller bonus to compensate. What you don’t want is one of the trials lol now that’s a mother matter.
Could be wrong tho as I’ve not done the math, just what I’ve been told when levelling and having similar complaints