Do you people bother reading about the issue?
THIS DOES NOT INVOLVE AI.
Uniform+vest is affected. Headgear and backpack is not.
NO MODS HAVE TO BE PRESENT FOR THIS TO OCCUR. You can flame digital all you want @z80cpu but you didn't bother to actually read what he said. Vanilla Arma. No mods. No AI. PLAYERS are affected. Agree with whomever you want, its still wrong.

I'll say it again, although I doubt you care. One proven way to reproduce this is entering a vehicle and switching seats. It's very important to note that the issue doesn't appear immediately but a while after.

Caused by changing seats in a vehicle. There, now you have a very specific thing to investigate, get to work ;)