When someone in an online
video game teleports back to where they were before because of lag.
Packet loss or generally bad internet is usually the cause of this problem. To make the game feel less laggy, when the game client sends packets to the server about your character moving, it will show your character moving on your screen before it has actually verified that the server knows you moved. In rare cases, those packets are not received by the server because of packet loss or just delayed by a large amount of time because of high ping. In that case, the server doesn't know your character moved and will sooner or later send back a packet telling the client about the actual position of the character (
the position you were last time the server received a packet). On your screen , it will then look like you suddenly
teleported back but the server thinks you were always at the position you
teleported to.