Also got this 3 times since some days.
It happened when jutsu end or changing map, the map is shaking as there is a bomb somewhere (?) and health and chakra bar are updated with reduced value (like if we don't get the bonus from guild).
When it start to happen, it keep happening until we restart the client
Today it also started just after having done relaxing spa mission .. (don't remember previous times)
It just happen again when leaving med corp, but doesn't repeat after changing map .. look I don't need to restart this time .. also try to understand why it happen but it's a strange one