I do sweat there more. That may lead to the feeling of cold. I had a softball sized hernia right there until last week so we will see what happens with that being gone.
You might need to adjust the straps if it’s compressing your insulating jacket that much. If you’re alternating between moving a bunch and then stopping and glassing, I prefer to wear my bino harness over my base or mid layer, then put on my puffy when glassing and remove my binos from the harness and put them on a tripod.
I can't say Ive noticed it but sure it makes sense, especially if your talking a lightly filled down jacket.
I have on occasion just thrown my big down puffy on over my bino harness, which I guess would technically be warmer but then Im always fighting the bingo straps coming up around my neck when the puffy is zipped up tight.
I wear the AGC bino pouch. Love it but I feel like it crushes the insulation in my Sawtooth jacket or my Unpronounceable in the body where the straps and pouch sit. I do like it slightly tighter so it doesn’t bounce around which might be part of the problem. I was just curious if others had experienced this.