There are certainly some cleat and obvious changes that were made between the point where the marketing began and the film was released.
There are scenes in the trailer below, such as a student stabbing themselves in the eye, that simply are not in the final cut of the film.
While the source of this information is being left vague, likely intentionally so, so we can’t confirm it, if true it certainly sounds like the troubled production that we had heard about previously apparently lasted for the duration.