Ya, that is wierd. Either a complete misplay by Johnson or some odd bracket coverage.
Fuller doesn't care about the right side of the field at all. I assume he shading inside on the original number 1. That is the complete focus of his attention in the play.
Johnson looks like he overplayed a run fit, then took five mins to figure out what was going on around him, and never cares that someone is behind him. Johnson is clocking Kamara while Carr looks the other way, then works to the receiver in the middle of the field. I have to think he does not believe he has any deep responsibiity on this play.
Maybe Johnson was responsible for any vertical routes by the number two and deep/inside help. He plays Kamara possibly going deep, then plays inside on the original number one, who is now the 2
I doubt Witherspoon lines up tight with no help behind him. Asking Witherspoon to cover that route is ridiculous with no help.