Now if White had some time to arrange his pieces he would have a good case against the isolated doubled c-pawns. As it is, however, Black is easily quick enough to resolve matters and exchange the weak pawns, while preserving his pair of bishops.
Black decides to transfer the king to the other wing because it will not be safe on the kingside. In fact, he should have started preparations for this on the previous move, when he retreated his knight from d7 to b8.
Immediately switching his attention to the queenside, trying to open up lines there.
After the text-move the black king proceed safely to b6. Both players kept the position closed and soon acquiesced in a draw.
Clearly, the presence of the queen on h4 and that of the bishop on d6 could be an incentive to hit upon this maneuver.
Now the force of the maneuver is immediately clear, and already White is in dire straits.
A remarkable decision! From a Catalan opening the a5-bishop has been pressing against the c7 -pawn, and now Black voluntarily exchanges its defender. However, with this exchange, it becomes more apparent that the a5-bishop is off-side (note that there is no return because earlier White had followed up the bishop's move to a5 with b2-b4) and that Black is a piece up on the kingside. 23...c6 was also an option, keeping ...Bxc3 in reserve.