Hello,
I guess it should be almost easy for a network engineer to modify the packets on the fly to create a desync, but my guess would be this guy found a flow in TE (maybe he always opened the menus or the replay ?)...
Or it's just a big coincidence, which is still possible...
It's also possible that when you opened the chat, it reset something, thus removing the desync, it's hard to be sure what happened exactly...
