Since several versions of Arma 3 I've noticed an issue with the RCO-Scope. In some screenshots below you can see this pretty good.
(This also occures with the Apex-Khaki-RCO, ARCO and the MRCO):
DayTime:
https://i.gyazo.com/abb114473e377df30d4ec61bf7f3fcdb.gif
https://i.gyazo.com/cfb205b97ad863cfd07bda8ce77cba5a.png
https://i.gyazo.com/feca6f49f9ddff7bd6ce0f912e74ea97.jpg
NightTime:
https://i.gyazo.com/24288d9e2eb4f62d1ba80f7b54c5ade9.jpg
https://i.gyazo.com/e0f05e44b3eb57e1c15c6cecc557b0a4.jpg
https://i.gyazo.com/9ae4e6330e08b4c1b2f17f561db03804.jpg