To beat soft zones you throw underneath and get YAC. For that to happen Josh has to give up on a big gain EARLY in the rep because the ball has to come out quickly. It goes against everything in him but he's starting to understand why it's necessary.
Mahomes has gone through this to an extent this season too, but he's Mahomes and he's ahead in his development and quick to adapt so it's not quite as pronounced, but the teams that gave him trouble played soft coverage starting with the Chargers playing Seattle Cover 3 and then others copied/adapted the Chargers film. Bills/Chiefs was a battle of two teams with the same game plan, they each knew they'd face soft zones and each tried to run but KC was better able to execute against our poor front seven effort.