I’m blaming getting owned for it.This has weirdly not received much attention by gaming news sites today. Some gamers have discovered a desync issue between Halo Infinite's local client and server's perception of what players are doing in game. This started gaining traction on Reddit yesterday, then 343 responded confirming the issue.
The video in the article demonstrates in footage how much drift can quickly be introduced.
So now when you miss that headshot, just blame desync.