The Mandela Effect. Your old videos on this subject, I am fairly sure when these started trending, that is how I originally found your channel.

There was a Star Trek The Next Generation Episode, where Whoopi Goldberg's character was the only person on the ship who knew the timeline had changed. It was obvious to her because Lt. Yar was supposed to be dead in the proper timelime, yet she was still alive in this one. In the end (spoiler), Yar enters the anomaly on a ship from the past, and it is believed she retains her memory from this false alternate timeline as she enters the past of the original timeline. The original timeline is restored, but now Yar has been re-entered into the past with a memory of events in a future that will no longer happen.

My theory, if Mandela Effect is real in some cases, it might be similar to how it was on Star Trek. Either a person is switch out of the their previous reality, or the physical thing that never existed is somehow replaced into our shared past experience.

Another solution, on the quantum level of bizarreness. Time and reality are so closely related. Time erases past realities and constantly creates new ones to replace them in a slightly evolved/mutated form. It happens on the sub-atomic level where atoms and molecules can relate to each other in intelligent ways. It is possible that time's past imprint on the current reality can be altered with technological means. This might explain why we remember things that did happened, but according to things recorded by time's constantly remade reality, that part of the past no longer has a molecular thumbprint in the current reality. How it doesn't disappear, and changes intelligently from one strange thing to a similar strange thing, I have no idea.