When I fired about 10 shots in the red box area, the AI sniper in the black box area started shooting at me non-stop. Does that make any logical sense?
The in-game time was around midnight, the visibility detection distance was 14m, and I measured the sniper's distance from me with a rangefinder at 240m.
There were no other players on the server, and the weapon I used was a suppressed SKS.
I have noticed that currently, after you fire just a few consecutive shots, all AI immediately detect you — there is no significant difference whether you use a suppressor or not. The most extreme case so far is this one: an AI 230m away was able to quickly detect me at night. Once night falls, the AI's vision is far superior to mine. Even when using the most expensive night vision goggles and IR illumination, I still cannot gain good enough visibility for a fair fight against the AI.