<R8> Teams may add non-functional decorations, provided that they do not affect the robot performance in any significant way or affect the outcome of the match.
Robot elements which mimic visual elements of the field (such as the color pattern of the Flags), or could otherwise interfere with an opponent's Vision Sensor, clearly affect robot performance and could affect the outcome of a match. Thus, they would now be considered a functional element, and would not be permitted by R8.
This would be similar to using a giant decal. By itself, it is considered a nonfunctional decoration. However, if used to hold metal parts together or to hold game objects, it has become functional, and is no longer legal.
That being said, just as teams are responsible for the decorations on their own robots, teams utilizing the Vision Sensor should be conscious of the possibility for inadvertent or incidental visual interference. It will be up to the inspector and head referee to determine if a given robot's decoration or design acts as a "Vision Sensor distraction" or not.
R7 and R8 will be updated in the June 15th game manual update to state this more clearly.