I have a simple effect for limiting carry capacity. It changes player speed attribute:

{ "effects": [ { "type": "attribute", "effect":"generic.movementSpeed", "min": 1, "max": 500, "percent": true, "id": "effect.moveSlowdown", "amount":-0.05, "modifierType":0 }, { "type": "attribute", "effect":"generic.movementSpeed", "min": 1.1, "max": 500, "percent": true, "id": "effect.moveStop", "amount":-0.05, "modifierType":0 } ] }

If the player has the first effect on (carry capacity exceeded) and is moving at half speed and then logs out and closes the game, this attribute gets stuck to them. If the player relaunches the game and joins the same world, the speed is halved even when not carrying anything. The only solution now is death.