That's the thing @Tai_Le
From tear down videos I saw it looks like there is no rule there, there are Snapdraggon units with copper heat pipes, and graphite heat pads, and there are Exynos units with either too. Appears to be completely random. I suspect they just used whatever was available since the pandemic has affected manufacturing of components all over the world. They likely decided both solutions had similar thermal properties, and none of us would ever know which one we actually got. And honestly, this might be the reason why some people are seeing high temps while others don't.
Could you show me the video Snapdragon use copper cooling system?
In the Channel 'JerryRigEverything', Zack is wrong, his phone is Snap comes from Korea, not Exynos. And it uses Snap and graphite cooling.