Desync is a video game term that means the player’s input to the game does not match what is happening on their screen.
There are many causes of desyncing, and some fixes that can help relieve it. “One of the most common issues that can cause order problems in V2V games such as Dota 2 or LoL is packet loss” explains Dave Barclay from Valve. Packet loss occurs when information packets are not delivered correctly, and so faster internet speeds will usually help reduce packet loss which will hopefully alleviate any order issues your clients may have been experiencing.”