On Polar Highlands you see a moving dot in 2 km, you aim it, press "E", move your mouse cursor to "enemy spotted" button ...and it's already gray, because ...this mechanism sucks!
Actually, showing target in your crosshair as "target spotted", when "E" is pressed, would be the best variant IMHO.
Edited by Geravind, 12 July 2020 - 11:11 PM.