So the problem occurs when you down a FT player. Once FT member is downed his hitbox becomes messed up.
Proof: Watch this short video
THIS HAPPENS WITH ARROWS/SPEAR THROW/DISC and probably every other ranged weapon.
Just look in the video at 0:15 and then at 0:18 right after - I shoot the moving FT member but my shots hits a downed FT at whom I wasn’t even aiming (you see that the “hit marker” gets red, not white). RED hit marker - you Down a FT member OR you hit downed FT, WHITE hit marker - you hit FT when he’s not downed.
Downed FT still have “STANDING/CROUCHING” hitbox (it’s just invisible). There were so many times when I would try to headshot a downed FT just to see my arrows miss completely - even tho my crosshair was right on their heads every time. To headshot a downed FT you actually have to aim above the center of their downed body, to hit the “imaginable” head - as if FT wasn’t downed/lying on the ground but was crouching.