strange puzzle

In this puzzle : fr.lichess.org/training/62501
Black reaction doesnt follow stockfish analysis and advice.
After Qg4, black castles instead of Kc5, giving a clear but unnecessary advantage.

to distinguish between King and Knight, the correct notation for a knight move is N. so Nc5.
also it doesn't matter what black plays because the advantage is already gained the moment white makes the correct move.
shifting evaluation from +3 to +4 doesn't really make much difference.

thanks for the correct annotation, I didnt know that.