Regarding the dragons technique to cover the moon , we had two ideas. The first idea was to hide the planet itself, based on the project that Lusalim participated in. The dragons considered it a temporary and insignificant solution because it would only delay the destruction. Eventually, the cosmic catastrophe would still realize their existence. So they came up with a second idea: cognitive manipulation. Instead of literally hiding the planet, why not make it appear dead and barren from the outside, so that the cosmic catastrophe would simply overlook it? They tested this approach as well, but it also failed.

At first, I kept wondering which of these ideas the HP might have used. Then another thought came to me: what if they used both, but for different purposes? For example, Teyvat could have been physically hidden from the outside using a veil that would correspond to the first idea. Then, on top of that, the Heavenly Principles created a cognitive illusion affecting both those outside and those inside Teyvat. People inside Teyvat would look up at the sky and perceive it as a completely natural sky, so humanity would believe their world was normal and never question whether anything existed beyond it. we’ve already seen throughout the Archon Quests that almost nobody knew about the false sky. Even we, as Descenders, only learned about it after the Fatui brought it up.  Meanwhile, anyone outside Teyvat would perceive it as nothing more than empty space as if nothing existed there at all.   
I’m basing that part on what the voygar said in Nicole’s set.

But there’s a problem , for the second idea to succeed and look as real as possible , they need a the foundational laws of reality to first pervade that world. And that’s why I’m guessing that’s the reason why the HP changed teyvat’s law

What do y’all think?

What method did the HP use to cover teyvat?