That is Goku’s kamehameha, clear as day.
This is what a hadouken looks like.
Street Fighter’s Ryu thrusts his arms forward in one fluid motion, then pulls them back in. What Smith-Schuster did was much more drawn out. Look at him hold that pose. Just like Goku. Here’s a demonstration.
But however confused people might be by appearances, we know for a fact it was a kamehameha because Goku is Smith-Schuster’s favorite superhero.