AI still capable of pinpointing the player's location within seconds of firing. It's ridiculous. More to come, including YT video explaining in detail, later.
It's neither visual (you can fire whilst they're looking at you) or audial (you can fire whilst in close proximity), but the moment the bullet actually lands in very close proximity to them, they instantly become aware of the shooter's location.
They do this even without optics, in a situation where the player is camouflaged, shaded, 500m away, and prone. They have several km^2 of landscape to scan for snipers and yet they instantly locate not only the direction but the exact location.
Upon locating the shooter (in a handful of seconds), then then begin to return fire, often at a rate of only a shot ever 3 or so seconds, but with each one more-or-less guaranteed to hit. A player using the same weapon at the same range would find this feat extremely difficult to near-impossible, if they could locate the shooter first (which they wouldn't before being shot).
This even happens on Recruit difficulty with the entire squad set to the lowest skill bar level possible. {F23296}