the only movement he had was the weight shift on the adjustment to the ball on the comeback.
He even had possession for a split second.

If the defender hits anything besides his arm with his hand on the angle that he did, which was the only option the DB really had because he was mostly shielded from the ball, that is most likely a catch. It was a great defensive play, that likely ends up a catch on 8 out of 10 defends from the same spot if Tanner starts with the exact same catch. To hit his arm at an angle to get that kind of leveraged force on the ball is basically like trying to hit a baseball with a bat while jumping in the air.