Black has a four on row 7 — and the completing stone would also build a four on the diagonal, which on any other day would be forbidden stacking. Rule 9.7 settles it: a five overrules every forbidden pattern. Take the five and the game is over before the foul is even judged. Mind the precision, though: the forgiveness covers an exact five — a move that only overlines, six or more with no five completing, is judged, and judged fatally. This is why white must always count black's fives before counting black's fouls — the win check comes first.
Finish this step to move on.