Keeping AdvancedRobot instance in static field

When keeping AdvancedRobot instance in static field, robot will show warning:

Static references to robots can cause unwanted behaviour with the robot using these.

However I've been using this pattern (the way robocode can't detect, and I cannot avoid as well) since the first day I write robocode. However, robocode did not mention what's wrong with this pattern. Do anyone know what's the exact meaning of this warning?

I think the risk is that the static robot reference is not guaranteed to be valid after a given round, so if you don’t update the reference things may not work as expected.