A lot of people talk about Nibiru when they try to understand what's going on with the Shift, or with the Mandela Effect. They are worried about it being a planet in orbit around our world that will come and somehow destroy us. This is just a story.
Nibiru is not causing the Mandela Effect, or even related to it. It's a space station, a ship, that's parked in orbit around our planet. It is the vessel in with the Anu first came to our world, roughly 300.000 years ago, and where they lived during much of their time with our world. As the Anu set themselves up as gods, people came to refer to the place they lived as "the heavens" or "the dwelling place of the gods".
One of the reasons why Nibiru often gets linked with the Mandela Effect, is that the changes in our world are bringing back memories of humanity's ancient past.