This is normal because ABS keycaps that come with the keyboard are easy to get greasy after usage for a period of time. If you do not like this, it is recommended to replace them with PBT keycaps, which will be more durable and oil-resistant.
There is an obvious de-coloration on my K2 keyboard where all my grey keycaps and some of the dark grey keycaps are. Is this a manufacturing defect?
