TTK (time-to-kill) and TTD (time-to-death) disparity have been plaguing the series for the past several iterations. I think the worst offender was BFV. The problem is related to the netcode and how the projectiles are getting stacked up into single packets before they arrive at the receiving client. This is sometimes referred to as a super bullet. High ROF weapons are more likely to experience the problem.
If an automatic weapon fires at 800rpm It means that a bullet is arriving at 13.3 second intervals. Depending on the tickrate of the server it can leave little to no room for packet buffering, client delay, or the server simulation itself.
If the server tickrate is 60hz it means that the server's so-called frametime is 16.6ms. That is roughly how often the server can updates its simulation. This can vary depending many factors. There is also the concept of client and server update rates. These are how often the server will send and receive updates to and from the client. In most modern game engines these are dynamic depending on game state (things like relative player position). These techniques have to be used for scaling.
All sorts of variables can cause issues with TTD. Paacket loss from client to server, network congestion causing buffering, server underperformance, netcode bugs, differential delay (e.g. high-ping vs low-ping players) etc. can all cause issues.