Positionally talking a RB always needs to be there if a cross from the left wing comes. It's not like he did some outstanding. It's not even man marking tactic..it's zone tactic. Mar marking is something you don't see anymore in modern football. Yes Gabriel got no mark because his zone got no one. White needed to cover his zone and he didn't so well.
But it was Gabriel's mistake that forced Saliba to change his man last second. White shouldn't have even been required, Gabriel got sucked into the header Zinchenko was already heading for, didn't get there, and then couldn't get back in time. How you are turning Gabriel's mistake into White's is baffling. White's work there to cover was actually pretty good and he gets slaughtered for it
Notice how no one is saying Gabriel had a bad game even though he did make that mistake, and a few others?