I think it may be UK, as I can't find mine anywhere.
It depends on the country. Check out also the answer below:
There is no "African Passport". Africa is a continent, not a country. Countries issue passports.
The NSK passport is not a real passport. It is a type of "camouflage" passport and never intended to be a valid document for citizenship. Slovenia is not granting citizenship or passports for people other than Slovenians.NSK passport is not a valid document.
for camouflage
the probability relates to camouflage because how much of a color there is
it camfloges by its color
camouflage, their color pattern blends in well with the bark of trees
You can fly anywhere within the borders of your current country.
The traditional color is black, so it can be camouflage in the night.
its skin absorbes the color and changes to that color
Practically, it is safe to travel with a legitimate, valid passport of your country. If you are a dual passport holder then you use the particular passport for that country and the other passport for the other country. like if you are travelling to US then use US passport if you are travelling Canada use your Canadian passport.
Any colour can be used as camouflage so long as it blends in with the background.