In Q3 laps, Leclerc finally had a significant advantage over McLarens on straights. Basically, it was the biggest difference in Qualy ehen it mattered the most. What changed? The wind
As Piastri said in post-Q interview, it changed direction and made life more difficult in corners. What it also changed was the loss McLaren sustained in Q3 on straights
Even though Piastri still owned the corners in Q3, Leclerc's advantage on straights managed to neutralise this. Finally, it was down to different line that Leclerc takes in finsl turn and better acceleration on exit
What was a slight tailwind in Q2 became a noticeable headwind in Q3 - direction shifted from South to West and becsme a bit stronger too
Piastri felt it a lot, losing almost 2 tenths on main straight alone in Q3 vs Q2 lap. T2 was an improvement and for a while the lap is about the same. However, the final sector was a whole different story in Q3 and clearly neither Piastri nor Norris didn't get used to it quickly enough
Leclerc adapted better to different conditions and gained time in corners in Q3 vs Q2. He gained 3 tenths between T2 and final turn vs Q2, where Piastri lost 2 tenths vs Q2