How to explain the existence of the 1999 Immortal Incident?

Does not exist

Everyone involved fought fiercely with the aliens who were preparing to invade the earth. In order to fight, even the gods who were demoted to earth in 1999 participated. This fierce battle began in February and was finally won on December 27.

Afterwards, confidentiality agreements were signed and the memories of all non-combatants were erased. The incident in 1999 was sealed forever. It wasn't until someone mentioned it that it was finally slowly revealed by the people back then.

As for the truth of the matter, of course it is false. At that time, someone made a joke on Weibo to poke fun at the post-00s generation, saying that the post-80s/90s generation had made contributions that they were unaware of in order to protect the earth. Unexpectedly, netizens were extremely cooperative and made up related things in the comments.