The chess,com engine labels a move "brilliant " when it is the best move (or close) and it includes a sacrifice. In this case, Bxf4 is the best move, as it opens up the e-file and the rooks join the attack.
This whole thing with "brilliant moves", the whole of chess.com's "full analysis" is just a scam. No one should use it. You just swittch to the analysis tab, tick in the boxes "self analysis" and "show lines", and then you can see the real computer analysis with real computer lines.
Why is this move brilliant? https://www.chess.com/analysis/game/live/40111755345?tab=review lx4f