Ulhumbrus: After 6...cxb4 Black has devalued his c pawn but how can White make this count? Grischuk's answer is to attack the pawn by 11 a3 followed by 15 Nc2 whereupon after 15...bxa3 16 bxa3 Grischuk has a c4 pawn against a backward b6 pawn on Giri's part, and the advantage if other things are equal.
However can Black improve on this?
In the position after 16...Rab8 Black would like his queen's knight on c7 so as to support the pawn advances ...b5 and ..d5.
This suggests spending a tempo on this move earlier.
At move 14 Black plays 14...h5, disturbing the king side pawns without necessity and this appears to start a completely unsound attack, perhaps hoping for ...e5 and ...e4.
It seems naive to assume that Grischuk - one of the strongest players in the world - is going to wait for this but it also seems naive to assume that this is a move which Giri would play normally.
Suppose that Black spends this tempo on 14...Rab8. On 15 Nc2 bxa3 16 bxa3 Nc7 White lacks time to play both 17 a4 to stop ...b5 and 17 e4 to discourage 17...d5.
One example of an explanation is that Giri went too far trying to win because he thought that Nepomniachtchi would be likely to win the tournament otherwise.
We can assume Giri's own explanation will provide a reliable answer.