I have really enjoyed Insurgency games, started playing Insmod what feels like a lifetime ago.
But as with Insurgency 2014, the AI in the coop modes can be stupidly unrealistic, not constrained by the limitations placed on human players (eg. time to ads, vision blurred/shaken by impacts/explosions/door kick, or vision obstructed by smoke, foliage or walls).
As far as I can tell, all my points about AI players from this post in Jan 2019 are still applicable.
The AI definitely "sees" players through the whole map. Easiest example, when playing Outpost mode on Tell, you can hear the AI shouts the second they spawn, "Enemy spotted", despite multiple walls/structures between the nearest player and the AI spawn area. My biggest frustration is their ability to shoot through smoke, considering how often the AI drops smoke grenades. At present, if a smoke is dropped in coop mode, I relocate until the smoke clears because I've died so many times to a single shot through smoke (see the muzzle flash in the smoke as I die, and camera pans to that location).
Also, Outpost on Crossing at Alpha, I regularly play on the 2nd floor watching the nearest spawn (to the east of A), from inside the doorway, but AI that spawn to the north will start peppering me with bullets through the wall despite me being behind cover since before they spawned. The vision range in the new night maps is also just unreal, you can be prone, in a dark corner behind cover, but an AI player will kill you at range without you ever seeing them.
To expand on AI ADS/aim issue: The AI players are not constrained at all by the time it takes a human player to raise their weapon and ADS. The number of pinpoint shots the AI hits whilst running is just unbelievable, specially given my previous point here. The AI player model clearly shows their weapon aiming nowhere near your location, usually at rest in their arms, aiming at the ground to their left, but they'll shoot and kill the player directly in front of them without the weapon even moving. Yesterday, playing Outpost on Crossing, I was spectating and watched a prone AI player fire a PKM into the face of a human player whilst facing 90 degrees left of the player that was killed. It's feasibly possible that this was a spectator glitch, but from my experience and feedback above, I doubt it.
Spawn protection for AI is still frustrating. Playing on Outpost on Hillside (Sinjar???) or Crossing, you can hold an AI spawn location, but the AI don't take damage for ~3 seconds at the start of each wave.
Throwables accuracy issue seems to have been improved, thanks. The Laser Guided Molotov is not nearly as bad as it was, but given my earlier point about vision (i.e AI wall hack), I still regularly see the AI throwing molotovs/grenades over buildings at targets they have no legitimate way of knowing are there.
About 1 in 5 RPG AI players will instantly fire an RPG whilst moving, with deadly accuracy, but the other 4 will stand in the open for ~3 seconds, enough time for a security player to notice and shout "RPG!".
I have a hunch/feeling that the AI are more forgiving on lower ranked players, but I can't say for sure. Just the number of times an AI player will 1-shot kill me whilst they are running or through smoke/metal sheet, only for them to then run backwards at my sub level 20 teammate and die, makes me literally say WTF out loud.
These issues with the AI really break the realism effect, and are really quite jarring and frustrating.
I am presuming that all of these issues have deliberately not been addressed to make the game more challenging / unfair, but it's just so frustratingly unrealistic.
Is it not possible to have AI profiles for different maps and modes?
So, for example, on Outpost Nightfall: AI can't engage targets until they are in visible range, or define a virtual "fog of war" radius for each AI player.