There is no requirement for a subset of something to have the same properties as the superset. Just because everything in our universe is interconnected is no guarantee that the same applies to the hypothetical universe in which our simulation is run. This is ignoring that the idea is that we can’t see out of the simulation, i.e., there is no uncontrolled information being inserted into the simulation. This doesn’t preclude static from the outside impacting us in some measurable way…such as a background level of noise that is pervasive in the simulation, like the CMB.
I don’t know if we’re in a simulation, but a lot of people smarter than me and more knowledgeable in the field have come to the conclusion that this idea isn’t falsifiable, and I doubt your proposal is a new idea for them. This leads me to believe they probably had a good reason to dismiss it, better than my points listed above.