Can you find a mate in one move?

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MaestroDelAjedrez2025
How can black mate white immediately?
I can assure you that it's not easy to solve this puzzle.
HINT:
There's only one move that's mate.
Congratulations if you can solve it  

kire137
This is the same puzzle but in interactive format. It's a bit hard to see when the board is static, like above. This should help.
HACKER_PRO_1979
Ummmmm…