Why is a bad move a brilliant move?

Hello, I was playing against the london system, but I remembered the moves wrong, so I blundered into a worse position, but game analysis gave me a brilliant move despite that move being an outright bad move. Why is that so?

1. It's equal before the move

2. I'm losing after Bf5

8. Qxb2

Brilliant ideas are never bad moves =)  that's a deflection idea with the bishop.  If he takes it, there's no way he can save the pawn and the rook, which combined are worth way more

No, I understand what you guys are saying, but the problem here is white actually has compensation and is winning. Check the analysis yourself

It's not the right move order for the bishop deflection so I was positionally worse after 6...Bf5

Good post!!! A bad move is a brilliant move. As you have answer your question yourself.

1. It illustrates whether the white queen will the bishop.

2. If the queen does not take the bishop and move to Qc1. 

3. If take the bishop, you can take the pawn and the rook. 

This is a problem with analysis at depth 18, where Bf5 is thought to be the best move. At a higher depth the engine realizes that Bf5 is not such a good move, but the game review only does a depth 18 evaluation so the feedback it gives you should not be trusted 100%.

What depth do you run your reviews at? That has a major impact on how moves are evaluated. At lower depth, the evaluation is good enough that Bf5 is considered the best move and since it sacrifices material, it's brilliant.

At higher depth, it would not be.

It may be because of deph then. I have my game review at 22 depth, so I thought it was high enough because the self analysis immediately saw that Bf5 was bad. 

Sometimes engines just don't know what's up =p

Game Review uses a specific engine, so it also possible that engine at the given depth evaluatted differently than the browser one. When I was looking at it, on mobile web and Stockfish 11, it evaluated Bf5 as best for a few ply.