Sometimes a white deposit forms on the ceramic of your kamado, see the picture below.
This involves moisture drawn into the ceramic. This happens more often in winter. You can polish away white (lime) deposits by treating them with soda vinegar. Afterwards, rinse or wipe it well with clean water. This can be applied to both the glossy and urban (matt) versions. Depending on whether the white deposit is thicker, you may need to apply this treatment (several times).