GTA Online, on the Original Heists, has the Heavy Combat outfits on the Humane Labs heist, and the Heavy Vest comes within it.
When equipped in the Heists, these outfits grant increased defense, but only during the Heists. The evidence of that, you can survive a direct RPG impact if you have full health (green bar) and the regular armor vest (blue bar) full while using the Heavy Vest. The downside, you can't run at full pace while the vest is equipped. If you equip the Minigun at the same time, you can't even jump, either.
The hidden part is, you can equip the Heavy Vest along with anything else - if you save an outfit with it - and use it on all the other Heists, if a) The heist setup/finale does not demand any specific outfit and b) The host explicitly chooses "Player Saved Outfits".
You could defend it is a Hidden Mechanic because it is poorly explained on the flavor texts during the heists, and most players ignore the details and rush head long into action.
GTA Online, on the Original Heists, has the Heavy Combat outfits on the Humane Labs heist, and the Heavy Vest comes within it. When equipped in the Heists, these outfits grant increased defense, but only during the Heists. The evidence of that, you can survive a direct RPG impact if you have full health (green bar) and the regular armor vest (blue bar) full while using the Heavy Vest. The downside, you can't run at full pace while the vest is equipped. If you equip the Minigun at the same time, you can't even jump, either.
The hidden part is, you can equip the Heavy Vest along with anything else - if you save an outfit with it - and use it on all the other Heists, if a) The heist setup/finale does not demand any specific outfit and b) The host explicitly chooses "Player Saved Outfits".
You could defend it is a Hidden Mechanic because it is poorly explained on the flavor texts during the heists, and most players ignore the details and rush head long into action.