Cursor stacking can also become messed up without actually becoming desync'd in such a manner that anything becomes unusable.
I do not have a way to make it happen off hand, but it most often happens when doing tradeskills.
I was speeding through (manually not with MQ2) making something, drinks i think, and then went to give some to another player and they received instead one of the components I had been using. My inventory was seemingly normal, but upon camping and coming back some of the drinks i had turned into a component.
Along these lines I've also ended up with a bag in a bag
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