Like if we think about it, you could reasonably theorize Zukoās apparent lack of skill next to Azula is not just a gap in talent, but a difference in disposition. Zuko naturally gears towards traits the Fire Nation disdains, so, it follows it would affect his Firebending.
People see Zuko surrounded by prodigies and think that means heās a bum like he wasnāt moving like this even pre-Dragon