Why was this a brilliant move?

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Avatar of Revenant_Main

https://www.chess.com/analysis/game/computer/387337880/analysis?move=70

I was just going through a review of a recent chess match and apparently this move in particular was brilliant. To me, this move looks like it should be a good move or a mistake because I lost material (my rook should have been capable of more than their bishop, no?). I don't think the move completely shifted the state of the match either. Is it just because the bishop posed a bigger threat to me in the endgame than I thought, or is it something else entirely?

Avatar of Niikotine

Ok