This makes four different leaders in four rounds. After rounds 1 & 2, Fabiano Caruana led the tournament. After round 3, he shared the lead with Levon Aronian, while after round 4 Magnus Carlsen was the sole leader. After round 5 Aronian took over the sole lead, but now Alireza Firouzja is in clear first after six rounds. Only Jan-Krzysztof Duda and Aryan Tari haven't experienced first place in this tournament (and are extremely unlikely to do so, if it it's even mathematically possibility [it may be for Duda, but not for Tari]).
Round 6 was a reprise of round 5, but with colors reversed, and 2/3 of the results were also a reversal. Magnus Carlsen bounced back from his loss to Duda by crushing him handily, but Caruaan was in trouble with Black against Aronian until the latter went a bit nuts with 23.g4. This both gave away his advantage and introduced risk to his position where they had been none - and spent so much time on that move and the two preceding and succeeding it that he entered serious time trouble as well. Had he played 23.Ng5 he would have enjoyed a great advantage; instead, the position was equal (though very sharp). Aronian played very well after that to hold the balance in an insane position with almost no time on his clock, but he finally cracked. His 34th move was inaccurate, and his 35th move - which he probably had in mind when playing his 34th - was the losing move. Perhaps he overlooked Caruana's final move of the game - if Caruana didn't have that resource, Aronian would have won - or maybe he thought that 38.Nd6 would win, but then 38...h6 would keep Caruana on top.
Aronian is still a point ahead of Caruana, but trails Carlsen by a point. The tournament leader, however, is none other than the 17-year-old Firouzja, who did not copy the pattern of the other matches; instead, he finished his sweep of Tari, and he now leads by a point.
The next round continues the arpeggio pairing system, repeating the round 4 pairings with colors reversed: