I've just noticed this, and it means that all my crafted armour and weapons have far lower stats than they should. As soon as I put on the Srkaag gauntlets and boots, or the Starling Helmet, all of my items stats go down.
When I take them off, my item stats are permanently lower. I've been crafting things this way for ages, probably half the game, and so I'm pretty bummed about this.
It's all three items that have this bug, not just the helmet, as far as I can tell.
I guess the bug never got resolved?