There already are known many trans-neptunian bodies whose movements are synchronized with Neptune. Pluto is also among those.

However all the others are closer to Neptune, therefore the ratios between their revolution periods an that of Neptune are relatively small rational numbers, while for this new object the ratio is 10, which is much greater.

So for now, it is one such object among many, so it may be called "rare", at least until others are discovered. In any case it was unexpected that resonances still exist at such distances.