I think that relics with different ratings, although they have the same stamina data, actually hide the decimal part, So when actually playing, the cumulative data obtained after some rounding is different.
Yep, you need 76 blessing value for ‘true’ +3 stamina curios that actually give you +3 stamina in the live game. Because for whatever reason in the patched version of the game the Meatgrinder runs 75 score curios actually work like they claim and give you +3.