In general its not pr say a visual bug, your client simulate what the other user see based on the network traffic through the common server as if youre him, some things will be different be it movement, recoil or what not, but I do think you only see the verified desided network packets instead of what his client see so you might see a different picture then he does.
For instance if you meet someone in a shootoff, you have 37ms latency and the guy you meet has a really bad "hair day" so he is running 376ms latency. When he shoot you your client and his client normally challenge the server about whos packet is the most correct one (there are several models used for this in games but this one is used quite a bit, so using this as an example), the one where you are behind the door or the one where he sees your door is open. The server takes a desision and sends the correction to both clients and the inspector. This might adjust the truth a bit for the one inspecting so things look a bit off at times. Same this explains why someone can get "downed" and then pops up again in some odd cases, or you get hit behind the corner or stone sometimes, its not always cheating it might just be someone with an awfull network that the server choose to believe the client packet of. Just remember two clients can have a different picture of the situation and the server choose which one he believe, and propagate this to the onwatchers, that is why it can look like a gun is pointing the wrong way while you get beamed and so on in game. Its not always cheating, sometimes its just the internet hehe.
There is not much you can do about this, only thing Ive seen some competetive shooters do to minimize this is to have latency matchmaking, so people with 0-50ms latency match-make with each other and people with 500+ match-make with their own like its a part of the sbmm routine.
In general someone with no recoil mod you will see every bullet go at the exact same spot more or less. For the "visuals" of a latency glitch you will typically see the gun perhaps point the same direction without moving while the bullet scatter a bit.
I am generalizing here, I just described one of the techniques, there are many ways of doing this and for the inspector all will have side effects if you dont get to listen in on the specific signals from the client itself as when it comes to the visuals its the client that deside what to show not the server in most games (yes there are some where rendring signal comes from the server, but I am quite certain this is not done by Apex)
