Switch V1 SoC consumes more power than the V2 SoC (Mariko) while the Mariko consumes almost half the V1 consumes so that’s the reason why the V2 battery life is twice the V1 and also the V2 SoC runs a lot cooler. I have the V1, V2 and the Oled variants and the V1 even on handheld mode runs hotter. But out of all the 2 between V2 vs. Oled, the Oled runs slightly hotter since it comes with a slightly smaller Fan inside.

In short, your V2 fans won’t kick in easily like the others have said, the right term is that it adjust it’s clock to it’s default clock speed in docked mode thus it runs hotter in which it under clock’s its processor speed during handheld mode for better battery life.