Discolouration to any type of bamboo or wooden flooring is usually due to water damage. If water or liquid is left to soak into and penetrate your floor, the bamboo will absorb the liquid and gradually over time may change colour and distort slightly.
Preventing water damage to your bamboo floor is simple; wipe away and clean any spills or accidents as soon as possible and ask everyone to remove wet or dirty outdoor footwear before walking on your bamboo floor.
If your bamboo floor has already started to become discoloured through water damage, unfortunately there is very little that can be done as the planks of flooring will be have sustained permanent damage.