This is the play:
https://on.nba.com/119A6hQ
I don't know if Kanter actually did anything wrong here. It's clear the Jazz had been instructed not to double Anthony all night, and Kanter's guy had pulled him quite a bit away from the ball. I recall this same exact thing happening towards the end of the game with Favors/Hayward guarding Anthony.
Kanter's reaction is not slow. As soon as Gobert is beat, he comes over, but Anthony is too quick, sees Kanter there, and uses the rim as a protector for the lay-up.
edit: Here's the play with Hayward and Favors. Same exact thing that happened with Kanter happens with Favors here.
https://on.nba.com/119ALQg