It affects Seekers in Hide and Seek, on all maps as far as I can tell.
In Hide and Seek, if a seeker can’t find any hiders, after a bit, a random person will die and join them. The bug with this is that when the person who was chosen as a new seeker spawns in, they often still look just like their block costume, with cosmetics, but wearing armor.
I play on IOS, and my friend PadsCloud has confirmed noticing this on PC as well