An mp4 file was found on an Authority computer in Site-XXX without any records of anybody having uploaded/downloaded the video to the computer. This mp4 file is just a custom music video to Nothing is Real by Boards of Canada. The mp4 file's only anomalous quality is that it is anti-memetic.
At around the time when the mp4 file was uploaded to the computer, reports of the Mandela effect spiked with false memories suddenly being more common.
The story of the mp4 file is that it is from another timeline that is very close to our timeline, a timeline that is "adjacent" to ours. The term "adjacent" in this context is explained below
I was thinking of coming up with a term called "adjacency" (it's not completely relevant to the RPC story but I'll explain it). "Adjacency" is a measurement of how similar another timeline is to ours, and it's measured in a percentage, 100% being completely the same (a score of 100% wouldn't really be "possible", it would just be our timeline if it was 100%). So this mp4 comes from a timeline that is maybe 99% adjacent, meaning the timeline is very similar but not exactly… some minor differences.
At some point, our timeline and this 99%-adjacent timeline crossed. nothing really happens when timelines cross, except for that Mandela effect and some things from the other timeline being lost into ours. the differences in the other timeline are responsible for the Mandela effect; the timelines just "overlay" on each other, if that makes sense
The Mandela effect part is supposed to point toward this mp4 file appearing out of nowhere as a result of timelines crossing.
Finally, the reason the mp4 file is anti-memetic is that it does not "exist" in our timeline:
In the metadata of the mp4 file is a personal note allegedly written by the creator of the file, known as Milo Ricketts. Milo gives some information about himself, such as a link to his website, the schools he went to, and the one he goes to at the time of the video's creation. He as well states his parents' identities. He further explains that the mp4 file is to be part of a time capsule that he will make, hence why he stated such personal information; to preserve his identity.
The Authority investigates the name of Milo Ricketts in the schools he stated, as well as his parents. Records provided by the schools do not show the name "Milo Ricketts." The Authority was however able to find the parents, who were then questioned. The parents end up telling the Authority that they "never had a son." The website link that Milo gave also did not lead to any website.
At the same time as this investigation, the Authority is researching the spike in the Mandela effect and figures out that our timeline and an alternate timeline crossed. Using the date and time at which the mp4 file first appeared, they figure that the mp4 did indeed result from the timeline cross.
So in a way, the mp4 file doesn't exist either because, well, Milo was never born in this timeline. There was no Milo to make the mp4 in this timeline. It should not exist here.
So in an attempt to "correct" this paradox, the mp4 file took on anti-memetic properties to make it forgotten - as if it never existed.