I didn't see Odegaard's level up coming either. I was one of his biggest critics - called him out several times for lacking a needed killer instinct in front of goal, and being pushed off the ball easily. And then it clicked and he started delivering with end product regularly, and using his technical superiority to keep the ball better.
From what I've seen (admittedly not much), and the stats I've looked at, if we can nurture a similar upward trajectory in Havertz we'll be laughing at his price tag in a couple of years.