They really should.
There's cheese they need to fix that will be completely out of whack with level 5 characters. Like lvl 5 Fighters doing alpha strikes with invisibility potions with two attacks and Action Surge (max 6 great weapon attacks before enemy gets a turn if you also win initiative?).
Or level 5 Wizards long resting after every fight and Fireballing away. 3rd level Magic Missiles are going to be so OP with a certain amulet as well (~30 damage a shot with 100% hit chance).
Spell UI should be redesigned as well before casters hit level 5. It's already messy and confusing with just two levels of spells.
