I have found boveda packs to me at least alter the smell to some degree. If was to take a guess It is the natural quality of salts they use. However I do in fact still use them for long term storage regardless.
Take anything a say with a grain of salt. I have grown the headband 2X stretch. Maybe 10 weeks. It was kinda hungry Absolutely covered in trichomes. Everyone that smoked it liked it. Most said it was tasty but oh god did it stink most certainly required smell proof containers.