Use the attached repro mission
1. Go prone and crawl under lush bushes in front of you
2. Set your optics zeroing to minimum (300 m), soldiers are ~270m away.
3. Make a well aimed killshot at a soldier that is not a leader* that will take out that soldier immediately
4. All AIs will know your position and start firing despite no human being able to spot a sniper in ghillie hiding in bushes that fast... especially when facing away when the kill happens
*leader needs to give an order to attack you otherwise nothing will happen