I kidna skipped the pre-blue vortex, how did Eida even did this? and why have she not decided to reverse everything back?
Save you some time.
How did this happen? Eida used a shinjutsu (god technique) Omnipotence.
What is a shinjutsu? Ohtsusuki have access to god like abilities from mundane phenomenon like making it rain to higher dimensional abilities.
How did Eida get this ability? Kind of a 3 parter.
1. The goal of the Ohtsusuki is to ascend to a higher life form. They do this by eating planets. Via the tree. Doing this enough times and they evolve and leave their physical body.
2. An ohtsusuki named shibai completed this ascension. It's been a minute so I can't remember well but they need to eat enough planets and pknow/ be able to perform shinjutsu to ascend.
3. Jura found the discarded body of this ascended ohtsusuki and started harvesting his body and making amado implant shibai blood into the people of the group. 3 people of the group gained abilities from this. Eida Omnipotence. Daemon reflection and koji prescience (ten ways). The rest didn't awaken.
How does Omnipotence works. Desperate need or want sparks the ability. The world or universe (don't know its range) then reflects the user's desire. Though it doesnt have to be her desire. If she wants to help someone else enough it can be tailored to anothers wants. How it works varies on the desire. Eida desired to be loved so she gained an uncontrollable charm ability. Only ohtsusuki and family are immune. Kawaki wanted to swap lives with boruto so he could kill him and not have to fight a whole ninja village. So life swap. Their positions swapped in others views. The knowledge of the swap can be known but Omnipotence will constantly erase that knowledge from those who've been affected.