The mistake itself was pretty obvious. Instead of taking the hanging D pawn and exchanging one of the rooks to simplify the game, Sheva's impatience finally clouded his judgement as he pushed his G pawn forward, trying to break the deadlock and get a passed pawn on the H file. It was a decent strategy, but Arfan's knight was in such a good position to plant itself on the E6 square, getting supported by the pawn on the D5 square that Sheva should've taken earlier.
*Author's note: If you want to visualize the position better, check the comment below.
The evaluation bar shown on everyone's screen spiked up instantly, showing that Arfan had the immediate advantage due to the mistake here. It showed +3.5, meaning that the position was so good that the computer itself thought it was equal to Arfan having a three-pawn advantage here.
