What we call desync in video games is a sign that the game’s client and server may not be fully synchronized.
Desync can happen for many different reasons including packet loss, network congestion, or hardware issues such as graphics drivers. Sometimes it does not occur at all- if you get disconnected from either the server or an external player, then the game will likely go back to its normal state of sync since there is now no means of diverging between yourself and your peers. If on the other hand you disconnect from the local machine (yourself), then that divergence continues for as long as your PC gets out ahead of what your friends are seeing on screen – which is why this type of desync tends to lead to more severe problems.
While synchronization between peers is of course important to ensure that everyone sees the same thing on screen, it’s also the case that divergence creates extra work for both server and client which can slow down feedback loops and impede responsiveness.
