Unlike simulations of, say, climate, the universe being a simulation requires that every aspect of everything be quantified and that those quantities be stored in some manner. That storage would require a great number of physical storage devices to record the status of each subatomic particle. The storage for each particle is thus much larger than the particle, and the storage for the whole universe would be larger than the universe. But by definition, the universe is everything. Thus the size of storage (which is part of everything) is larger than everything. Contradiction, a thing cannot be larger than itself nor can a part of itself be larger than the whole.
Looking at it more generally, the universe being a simulation implies that there's something outside of the universe doing the simulation. But again, the universe is everything, and speaking of something outside of everything is nonsense.
To get around these objections, it must be denied that the universe is everything. At that point, the use of language has been rejected and all attempts at logic and communication are futile.