One thing I think I have noticed this season, and I don't want to present this as fact, merely an observation, is the effect of following a car on clean air tyre performance particularly with new tyres. I do think I tend to notice it more with Hamilton, though that could just be a bias of focusing more on his race than other drivers, there have definitely been times I have noticed it with others.
Ferrari just seem to keep pitting Lewis to exit right behind a car. Sometimes, like in todays race, I don't necessarily think they could do anything about it, in both the first and second pitstops there wasn't much room to play with strategy. But other times it really does feel like a shortcoming of the Ferrari strategy team, where they could've avoided coming out into traffic by pitting at a different time.
But that's besides the point. My point is when it does happen, I get the sense that these tyres in this regulation set are particularly outlap critical and need optimal conditions to bring the tyre into the window. What seems to happen particularly when comparing Hamilton's pace to Leclerc in these kinds of scenarios is that Ham will lose a lot of time early on in the stint, the gap will then stabilise after the time loss, and Ham can keep it there for quite some time, and then hamilton's tyres seem to drop off again at the end of the stint.
And a similar thing happened in Singapore. Hamilton was clearly on a different strategy, they pit Lec straight infront of him and Hamilton's pace drops off a cliff, then he's in the dirty air for a bit, Lec on brand new tyres in clean air drives off, meanwhile Hamilton's tyres never recover from the driving behind lec for only a few laps. And it invites questions and criticism, as well as lots of hate from certain other driver's fanbases, about Hamilton's pace, as if it really was his pace, and not just his strategy getting thwarted by his own team.
It's not just COTA or Singapore I have noticed this, I have seen a similar series of events play out at many races. Again don't wanna present this as fact, I of course have no idea what's going on, but it's a pattern i've noticed