Well, not exactly. Costumes can just be suffocatingly hot. Bulky, poorly ventilated, possibly used in an environment that isn't air conditioned. If the SFX crew for your movie is on their game, you have a cooling system built in and it's not that miserable. But I've heard stories of some people properly suffering in particular roles because it was just so goddamned hot.

If you go to a convention, like Adam is fond of doing, you're gonna be suited up for hours, without support crew. So it's gonna be tricky, and he makes money doing videos about tricky things...

That said, he did start with a surplus EVA (or was it fighter pilot?) base layer with the cooling tubes built in.