I saw this trend, FCB blaming FDJ in every loss. It's always his picture.
Now about the play.
Gundogan was marking Vitinha.
Both FDJ and Gundogan rushed to help Cancelo who was 1 v 3, FDJ showed Gundogan to press,
then spotted that no one is on Vitinha so he turns back and runs to block the shot but it was late.
The only guy who was free to mark Vitinha was Lewandowski.
Here you have 4 possible interpretations:
Gundogan is at fault for leaving Vitinha while FDJ was already heading there and not respecting the low block.
FDJ is at fault for not spoting the gap left by Gundogan and trying to coordinate Cancelo and Gundogan
Lewandowski is at fault for not rushing to mark Vitinha since Gundogan wanted to press.
Xavi is at fault for not telling them to keep the low block at any cost.
FDJ was scapegoated by the clap-trap since he was the closest player when Vitinha shots
For me it was a total brain fart and as a DM he had the duty to help Cancelo 1 v 3.
In a better managed team Lewandowski has the blame, but Gundogan having that experience maybe he should have predicted that we are a poor side playing in 10, same cand be said for FDJ.