Armor damage appears to be a valuable stat at first glance in The Division 2. However, it seems that the value is not functioning properly, as discovered by a player.
Here’s why armor damage is popular: The stat provides the player with a bonus damage against enemy armor. This allows players to destroy it faster and thus eliminate the enemy more quickly.
So it’s a direct damage buff that should have a positive effect in both PvE and PvP. However, that doesn’t seem to be the case in PvE, as one player has found out.

Armor damage seems to be bugged
This is what the player discovered: The user Fears_Revenge tested the utility of armor damage because he questioned its effect. He then posted his results in the subreddit of The Division 2.
According to these results, it appears that the value is currently not functioning in PvE.
This is how the test was conducted: At the shooting range in the operations base, Fears_Revenge tested the value directly on the target dummies.
This is shown in this screenshot of his test:

Each hit deals the same damage, the value currently seems to have no impact on enemy armor. He conducted the same test with NPC enemies in the Dark Zone and achieved the same result.
What about PvP? Strangely, the value seems to work in PvP.
In his test, he achieved 6407 damage per shot with armor damage, compared to just 5824 without it. That corresponds to the actual 10% bonus.

Thus, armor damage currently only has utility in the Dark Zone and Conflict modes. At least until Massive fixes the issue.
Not the only bugged value?
This is what the Reddit community says: Most responses are rather annoyed. Some players complain that there are several values and talents that do not function properly.
The armor stat is also not the first bug that has occurred after the last update:
This limits the choice of equipment. The user Zeus_Apollyon comments on this:
Honestly, I haven’t felt like farming so far because so much is broken at the moment. Why should I spend all my time farming for gear when I don’t even know if what I find works?
Source: Reddit
Most comments agree with this. Many actually love the game but feel held back at the moment by opaque and bugged stats.
The armor stat is also not the first bug that has occurred after the last update: