mafi natural wooden floors are finished with a non-film forming and open-pore surface treatment. In this way the wood is not impaired in its breathability.
But also note that wood is a natural material, which is influenced by the particular temperature and humidity.
At high ambient humidity, the wooden floor absorbs moisture and expands. When ambient humidity is low, such as during the heating season in winter, the wood releases moisture and shrinks - which leads to gaps forming.
The symmetrical structure of mafi planks massively reduces this effect, however it may still lead to the formation of gaps.
Don't see this as negative, but as proof of the naturalness of your wooden flooring. After the heating period, the gaps close themselves again.