Black naturally wants to capture with the bishop if possible.
12...dxc4? naturally taking back would lead to doubled pawns once again.
12...dxc4? naturally taking back would lead to doubled pawns once again.
and finally Black eliminates the doubled pawns next move. The position is quite dangerous for White since the two bishops are extremely dangerous along the a6-f1 and b6-g1 diagonals.
This is one of the main plans in these kinds of structures, opening the diagonal for the dark-squared bishop. Now the white bishops directly target the black king, and White's attack will be unstoppable.
17...Nxc4 looks super strong for Black, but White is winning after the precise 18.Qe4 g6 19.Bxc4 Qxc4 20.Qe5! f6 21.Qe6+ Rf7 22.Rc1
followed by d6.
followed by d6.
The black king is completely naked in front of so many attacking white pieces.