In 21w03a, taking an item off of an armor stand triggered a vibration. In 21w05a, that game event has been replaced by the more general "equip" event, which works for more than armor stands. However, it doesn't trigger when taking armor off an armor stand anymore.

As of 21w06a, an event is triggered when armor is removed. However, it triggers from the player's potion, not the position of the armor stand.