Stab is by default 80% of cut resistance and not necessarily explicitly defined in json.
Tempered steel chainmail vest torso values were 13.2/13.2/9 in stable G, and 7.2,7.2,3.6 in the latest experimental (and has been at least since august 23). You can select the version at the bottom of hhg.
Did you confirm the version you’re playing on where you saw those numbers? Do you have a copy of both experimental and stable on your device?