I'm really tired of the laggy killcam, most of the time it does not show how the other guy killed me, I either see the delayed gun firing with no sound/bullets, or I see him wave his aim over me and start firing right when I fall dead to the ground...derrrp!

The question is, what could be the cause of this? It's happening on pretty much every single killcam nowadays.

Who knows? Maybe it's a netcode issue, maybe the mechanism that records everything doesn't work 100% of the time and therefore when the killcam does play, it plays late due to lag or doesn't play properly due to lost packets. Faulty killcams also make it harder to judge whether someone used subtle hacks or was just a genuinely good shot. And fault killcams can trick people into making your legit kills into something dubious.

I don't know if there was official confirmation, but network issues could be the culprit.