I am always queued with the best players that know what to do in any situation , will always know what position you take and will totally headshot you if one pixel of your hitbox shows up on their screen. Why??? Can somebody explain?

So, I just noticed this and im not sure what the cause is. The shadows are like broken lines, its not smooth. Please help!! Here's the vid of the shadow thing im talking about, look at the shadow on the arms, fullscreen the video and you'l...