Yeah, I suspect you’re right about breathability and wind blocking. That was a major complaint
@mtwarden has had about active insulation layers up to this point - sandwiched between layers that don’t breath. That said, I’d suggest that even this is way better than the thick fleece midlayers of yesteryear. It’s really remarkable how well it keeps you comfortable - not too hot, not too cold - while allowing perspiration to move out and evaporate.
In October, I was field dressing a deer on the western face of a mountain in the afternoon with just my baselayer on. When the sun crested below to next mountain and I became shaded, the temp dropped really fast. All I had in my pack was the Beyond A3 because it had been warm the entire day. I was afraid I’d be freezing by butt of for the last 30 mins of cleaning, but the A3 kept me plenty warm. On the all-downhill hike out, I also didn’t overheat.