Cats with white moustaches (“mustaches” in American English) are not that rare. These cats do stand out. They have white fur along their whisker pads and then up and around like a fancy, old-fashioned moustache.
The white fur is caused by the Piebald gene, also known as the white spotting gene. This gene is present in solid color and white cats and any cat that has areas of white fur. White fur lacks pigment in the individual hair strands. A well known cat breed that has the piebald gene is the Snowshoe. There are others.
I am sure it is pure chance that the gene affects parts of the cat’s face that results in giving an impression of a moustache.
This is a handsome black and white cat and the piebald gene just happens to have affected the face as it has.
Apparently he is male and he lives with a friend of the photographer.