A major desync issue occurs when players put yellow storage boxes within themselves over and over or if you put backpacks within other backpacks. I believe the issue is related to having to many items which causes a proximity desync issue for yourself and other players around you.
I'm not certain if this affects the entire server in general but at the moment it does seem to cause a proximity desync issue for the player that has the items on them and anyone closely near them.
1 - Fill any backpack (30 slot or 35 slot) full of items.
2 - Put the full backpack inside of another backpack (it should take up 25 slots, leaving either 5 or 10 left in the empty backpack.
3 - Keep filling up other backpacks of items and putting them in other backpacks.
4 - Desync begins to occur for yourself very badly, not allowing to use hotkey commands 1 through 0, vaulting, opening doors, etc.
5 - Other plays in the vicinity (proximity) also begin to experience lag/desync issues, however if they go far from you, things begin to smooth out.