Why is this move a mistake?

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Avatar of bw88108

I play black, when I move on move 12, the analysis engine says that that move is a mistake, for some reason, even though I think that is is a brilliant move.

https://www.chess.com/analysis/game/live/104871777770?tab=review&move=12

Avatar of Martin_Stahl
bw88108 wrote:

I play black, when I move on move 12, the analysis engine says that that move is a mistake, for some reason, even though I think that is is a brilliant move.

https://www.chess.com/analysis/game/live/104871777770?tab=review&move=12

Basically, after your move white castles queen side and is going be able to come out ahead positionally, if you end up taking the bishop on c3.