Based on that information, El-Melloi II theorized that there was “a distinction between those infected with a disease-like curse, who had only their minds brought to that world, and those who were dragged into it by force, body and all.”
“It’s highly probable that the latter is the result of treating you as enemies. The former also appears to be a hostile act . . . but those affected suffer no physical harm, and there’s no indication that it’s using them in the Grail War. It’s probable that it’s simply using unusual means and has no hostile intent.”

Fate/Strange Fake: Volume 6, Interlude ("As Dream and Reality are Both Illusion II")