From what I've read about the theory, things like Deja-Vu, Ghost, Spirits, etc...are all "glitches" in the simulation.
8Visible Flaws
If a simulation is advanced enough, those inside needn’t recognize it as a simulation at all. If you were to grow a brain in a vat and manipulate it with stimuli,
it wouldn’t know it’s in a vat. It would assume itself a living, breathing, active person.
But even advanced simulations can have flaws, right? Wouldn’t we notice some imperfections, some “glitch in the Matrix”?
Maybe we do see such glitches in our everyday lives. The Matrix offered the example of déjà vu—when something seems inexplicably familiar, the simulation may be skipping like a scratched CD. Supernatural elements, like ghosts or miracles, could also be glitches. According to simulation theory, people really do witness these phenomena, and they do so because of bugs in the simulation’s code.
The Internet offers plenty of
anecdotal evidence of these glitches. Keep your mind and eyes open, and maybe you’ll see some for yourself.