It could be counterdesigned, but I agree, that would be a nightmare for any AI engine not specifically set up to do it.

I'm reminded of a novel that I utterly can not recall in general, but I'm thinking of a scene where someone realizes they're in a simulation because the sidewalk cracks are wrong. They knew the real scene there happened to be a shape (of what I can't recall) in the cracks, the simulation was showing random cracks.

I don't think it even requires a monotile. Just use an event-specific non-repeating pattern on a backdrop.