I've noticed that when playing, armoured vindicators will only attack me once when I stand still. Every other illager will still attack me, but armoured vindicators will just stand still and do their idle animation. I could attack them and other enemies, and as long as I was standing still, they'd still stand there until they died. The armour and weapons equipped does not matter for this, and I'm doing a default difficulty run right now.

Here's a video that was too big to directly upload.