From the article in the original post:

"Scientists noticed that rebel Niku seems to be hanging around a gang of other
strangely aligned objects. At first glance, the scientists thought that this
might suggest that Planet Nine, a hypothetical planet that would be about as
much as 10 times as massive as Earth, might be pulling on the objects.

But it turns out that the rebellious object would be out of Planet Nine's
reach, too free-living to succumb to the undiscovered planet's gravitational
attraction.

So exactly what's going on is still a mystery."

So, does mean there there could be a Planet 10 (& 11, 12 ..... ?) out there?